1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/ptrace.c
4 *
5 * (C) Copyright 1999 Linus Torvalds
6 *
7 * Common interfaces for "ptrace()" which we do not want
8 * to continually duplicate across every architecture.
9 */
10
11#include <linux/capability.h>
12#include <linux/export.h>
13#include <linux/sched.h>
14#include <linux/sched/mm.h>
15#include <linux/sched/coredump.h>
16#include <linux/sched/task.h>
17#include <linux/errno.h>
18#include <linux/mm.h>
19#include <linux/highmem.h>
20#include <linux/pagemap.h>
21#include <linux/ptrace.h>
22#include <linux/security.h>
23#include <linux/signal.h>
24#include <linux/uio.h>
25#include <linux/audit.h>
26#include <linux/pid_namespace.h>
27#include <linux/syscalls.h>
28#include <linux/uaccess.h>
29#include <linux/regset.h>
30#include <linux/hw_breakpoint.h>
31#include <linux/cn_proc.h>
32#include <linux/compat.h>
33#include <linux/sched/signal.h>
34#include <linux/minmax.h>
35#include <linux/syscall_user_dispatch.h>
36
37#include <asm/syscall.h> /* for syscall_get_* */
38
39/*
40 * Access another process' address space via ptrace.
41 * Source/target buffer must be kernel space,
42 * Do not walk the page table directly, use get_user_pages
43 */
44int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
45 void *buf, int len, unsigned int gup_flags)
46{
47 struct mm_struct *mm;
48 int ret;
49
50 mm = get_task_mm(task: tsk);
51 if (!mm)
52 return 0;
53
54 if (!tsk->ptrace ||
55 (current != tsk->parent) ||
56 ((get_dumpable(mm) != SUID_DUMP_USER) &&
57 !ptracer_capable(tsk, ns: mm->user_ns))) {
58 mmput(mm);
59 return 0;
60 }
61
62 ret = access_remote_vm(mm, addr, buf, len, gup_flags);
63 mmput(mm);
64
65 return ret;
66}
67
68
69void __ptrace_link(struct task_struct *child, struct task_struct *new_parent,
70 const struct cred *ptracer_cred)
71{
72 BUG_ON(!list_empty(&child->ptrace_entry));
73 list_add(new: &child->ptrace_entry, head: &new_parent->ptraced);
74 child->parent = new_parent;
75 child->ptracer_cred = get_cred(cred: ptracer_cred);
76}
77
78/*
79 * ptrace a task: make the debugger its new parent and
80 * move it to the ptrace list.
81 *
82 * Must be called with the tasklist lock write-held.
83 */
84static void ptrace_link(struct task_struct *child, struct task_struct *new_parent)
85{
86 __ptrace_link(child, new_parent, current_cred());
87}
88
89/**
90 * __ptrace_unlink - unlink ptracee and restore its execution state
91 * @child: ptracee to be unlinked
92 *
93 * Remove @child from the ptrace list, move it back to the original parent,
94 * and restore the execution state so that it conforms to the group stop
95 * state.
96 *
97 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
98 * exiting. For PTRACE_DETACH, unless the ptracee has been killed between
99 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
100 * If the ptracer is exiting, the ptracee can be in any state.
101 *
102 * After detach, the ptracee should be in a state which conforms to the
103 * group stop. If the group is stopped or in the process of stopping, the
104 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
105 * up from TASK_TRACED.
106 *
107 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
108 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
109 * to but in the opposite direction of what happens while attaching to a
110 * stopped task. However, in this direction, the intermediate RUNNING
111 * state is not hidden even from the current ptracer and if it immediately
112 * re-attaches and performs a WNOHANG wait(2), it may fail.
113 *
114 * CONTEXT:
115 * write_lock_irq(tasklist_lock)
116 */
117void __ptrace_unlink(struct task_struct *child)
118{
119 const struct cred *old_cred;
120 BUG_ON(!child->ptrace);
121
122 clear_task_syscall_work(child, SYSCALL_TRACE);
123#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
124 clear_task_syscall_work(child, SYSCALL_EMU);
125#endif
126
127 child->parent = child->real_parent;
128 list_del_init(entry: &child->ptrace_entry);
129 old_cred = child->ptracer_cred;
130 child->ptracer_cred = NULL;
131 put_cred(cred: old_cred);
132
133 spin_lock(lock: &child->sighand->siglock);
134 child->ptrace = 0;
135 /*
136 * Clear all pending traps and TRAPPING. TRAPPING should be
137 * cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly.
138 */
139 task_clear_jobctl_pending(task: child, JOBCTL_TRAP_MASK);
140 task_clear_jobctl_trapping(task: child);
141
142 /*
143 * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
144 * @child isn't dead.
145 */
146 if (!(child->flags & PF_EXITING) &&
147 (child->signal->flags & SIGNAL_STOP_STOPPED ||
148 child->signal->group_stop_count)) {
149 child->jobctl |= JOBCTL_STOP_PENDING;
150
151 /*
152 * This is only possible if this thread was cloned by the
153 * traced task running in the stopped group, set the signal
154 * for the future reports.
155 * FIXME: we should change ptrace_init_task() to handle this
156 * case.
157 */
158 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
159 child->jobctl |= SIGSTOP;
160 }
161
162 /*
163 * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
164 * @child in the butt. Note that @resume should be used iff @child
165 * is in TASK_TRACED; otherwise, we might unduly disrupt
166 * TASK_KILLABLE sleeps.
167 */
168 if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
169 ptrace_signal_wake_up(t: child, resume: true);
170
171 spin_unlock(lock: &child->sighand->siglock);
172}
173
174static bool looks_like_a_spurious_pid(struct task_struct *task)
175{
176 if (task->exit_code != ((PTRACE_EVENT_EXEC << 8) | SIGTRAP))
177 return false;
178
179 if (task_pid_vnr(tsk: task) == task->ptrace_message)
180 return false;
181 /*
182 * The tracee changed its pid but the PTRACE_EVENT_EXEC event
183 * was not wait()'ed, most probably debugger targets the old
184 * leader which was destroyed in de_thread().
185 */
186 return true;
187}
188
189/*
190 * Ensure that nothing can wake it up, even SIGKILL
191 *
192 * A task is switched to this state while a ptrace operation is in progress;
193 * such that the ptrace operation is uninterruptible.
194 */
195static bool ptrace_freeze_traced(struct task_struct *task)
196{
197 bool ret = false;
198
199 /* Lockless, nobody but us can set this flag */
200 if (task->jobctl & JOBCTL_LISTENING)
201 return ret;
202
203 spin_lock_irq(lock: &task->sighand->siglock);
204 if (task_is_traced(task) && !looks_like_a_spurious_pid(task) &&
205 !__fatal_signal_pending(p: task)) {
206 task->jobctl |= JOBCTL_PTRACE_FROZEN;
207 ret = true;
208 }
209 spin_unlock_irq(lock: &task->sighand->siglock);
210
211 return ret;
212}
213
214static void ptrace_unfreeze_traced(struct task_struct *task)
215{
216 unsigned long flags;
217
218 /*
219 * The child may be awake and may have cleared
220 * JOBCTL_PTRACE_FROZEN (see ptrace_resume). The child will
221 * not set JOBCTL_PTRACE_FROZEN or enter __TASK_TRACED anew.
222 */
223 if (lock_task_sighand(task, flags: &flags)) {
224 task->jobctl &= ~JOBCTL_PTRACE_FROZEN;
225 if (__fatal_signal_pending(p: task)) {
226 task->jobctl &= ~JOBCTL_TRACED;
227 wake_up_state(tsk: task, __TASK_TRACED);
228 }
229 unlock_task_sighand(task, flags: &flags);
230 }
231}
232
233/**
234 * ptrace_check_attach - check whether ptracee is ready for ptrace operation
235 * @child: ptracee to check for
236 * @ignore_state: don't check whether @child is currently %TASK_TRACED
237 *
238 * Check whether @child is being ptraced by %current and ready for further
239 * ptrace operations. If @ignore_state is %false, @child also should be in
240 * %TASK_TRACED state and on return the child is guaranteed to be traced
241 * and not executing. If @ignore_state is %true, @child can be in any
242 * state.
243 *
244 * CONTEXT:
245 * Grabs and releases tasklist_lock and @child->sighand->siglock.
246 *
247 * RETURNS:
248 * 0 on success, -ESRCH if %child is not ready.
249 */
250static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
251{
252 int ret = -ESRCH;
253
254 /*
255 * We take the read lock around doing both checks to close a
256 * possible race where someone else was tracing our child and
257 * detached between these two checks. After this locked check,
258 * we are sure that this is our traced child and that can only
259 * be changed by us so it's not changing right after this.
260 */
261 read_lock(&tasklist_lock);
262 if (child->ptrace && child->parent == current) {
263 /*
264 * child->sighand can't be NULL, release_task()
265 * does ptrace_unlink() before __exit_signal().
266 */
267 if (ignore_state || ptrace_freeze_traced(task: child))
268 ret = 0;
269 }
270 read_unlock(&tasklist_lock);
271
272 if (!ret && !ignore_state &&
273 WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED|TASK_FROZEN)))
274 ret = -ESRCH;
275
276 return ret;
277}
278
279static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
280{
281 if (mode & PTRACE_MODE_NOAUDIT)
282 return ns_capable_noaudit(ns, CAP_SYS_PTRACE);
283 return ns_capable(ns, CAP_SYS_PTRACE);
284}
285
286/* Returns 0 on success, -errno on denial. */
287static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
288{
289 const struct cred *cred = current_cred(), *tcred;
290 struct mm_struct *mm;
291 kuid_t caller_uid;
292 kgid_t caller_gid;
293
294 if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
295 WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
296 return -EPERM;
297 }
298
299 /* May we inspect the given task?
300 * This check is used both for attaching with ptrace
301 * and for allowing access to sensitive information in /proc.
302 *
303 * ptrace_attach denies several cases that /proc allows
304 * because setting up the necessary parent/child relationship
305 * or halting the specified task is impossible.
306 */
307
308 /* Don't let security modules deny introspection */
309 if (same_thread_group(p1: task, current))
310 return 0;
311 rcu_read_lock();
312 if (mode & PTRACE_MODE_FSCREDS) {
313 caller_uid = cred->fsuid;
314 caller_gid = cred->fsgid;
315 } else {
316 /*
317 * Using the euid would make more sense here, but something
318 * in userland might rely on the old behavior, and this
319 * shouldn't be a security problem since
320 * PTRACE_MODE_REALCREDS implies that the caller explicitly
321 * used a syscall that requests access to another process
322 * (and not a filesystem syscall to procfs).
323 */
324 caller_uid = cred->uid;
325 caller_gid = cred->gid;
326 }
327 tcred = __task_cred(task);
328 if (uid_eq(left: caller_uid, right: tcred->euid) &&
329 uid_eq(left: caller_uid, right: tcred->suid) &&
330 uid_eq(left: caller_uid, right: tcred->uid) &&
331 gid_eq(left: caller_gid, right: tcred->egid) &&
332 gid_eq(left: caller_gid, right: tcred->sgid) &&
333 gid_eq(left: caller_gid, right: tcred->gid))
334 goto ok;
335 if (ptrace_has_cap(ns: tcred->user_ns, mode))
336 goto ok;
337 rcu_read_unlock();
338 return -EPERM;
339ok:
340 rcu_read_unlock();
341 /*
342 * If a task drops privileges and becomes nondumpable (through a syscall
343 * like setresuid()) while we are trying to access it, we must ensure
344 * that the dumpability is read after the credentials; otherwise,
345 * we may be able to attach to a task that we shouldn't be able to
346 * attach to (as if the task had dropped privileges without becoming
347 * nondumpable).
348 * Pairs with a write barrier in commit_creds().
349 */
350 smp_rmb();
351 mm = task->mm;
352 if (mm &&
353 ((get_dumpable(mm) != SUID_DUMP_USER) &&
354 !ptrace_has_cap(ns: mm->user_ns, mode)))
355 return -EPERM;
356
357 return security_ptrace_access_check(child: task, mode);
358}
359
360bool ptrace_may_access(struct task_struct *task, unsigned int mode)
361{
362 int err;
363 task_lock(p: task);
364 err = __ptrace_may_access(task, mode);
365 task_unlock(p: task);
366 return !err;
367}
368
369static int check_ptrace_options(unsigned long data)
370{
371 if (data & ~(unsigned long)PTRACE_O_MASK)
372 return -EINVAL;
373
374 if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
375 if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
376 !IS_ENABLED(CONFIG_SECCOMP))
377 return -EINVAL;
378
379 if (!capable(CAP_SYS_ADMIN))
380 return -EPERM;
381
382 if (seccomp_mode(s: &current->seccomp) != SECCOMP_MODE_DISABLED ||
383 current->ptrace & PT_SUSPEND_SECCOMP)
384 return -EPERM;
385 }
386 return 0;
387}
388
389static int ptrace_attach(struct task_struct *task, long request,
390 unsigned long addr,
391 unsigned long flags)
392{
393 bool seize = (request == PTRACE_SEIZE);
394 int retval;
395
396 retval = -EIO;
397 if (seize) {
398 if (addr != 0)
399 goto out;
400 /*
401 * This duplicates the check in check_ptrace_options() because
402 * ptrace_attach() and ptrace_setoptions() have historically
403 * used different error codes for unknown ptrace options.
404 */
405 if (flags & ~(unsigned long)PTRACE_O_MASK)
406 goto out;
407 retval = check_ptrace_options(data: flags);
408 if (retval)
409 return retval;
410 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
411 } else {
412 flags = PT_PTRACED;
413 }
414
415 audit_ptrace(t: task);
416
417 retval = -EPERM;
418 if (unlikely(task->flags & PF_KTHREAD))
419 goto out;
420 if (same_thread_group(p1: task, current))
421 goto out;
422
423 /*
424 * Protect exec's credential calculations against our interference;
425 * SUID, SGID and LSM creds get determined differently
426 * under ptrace.
427 */
428 retval = -ERESTARTNOINTR;
429 if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
430 goto out;
431
432 task_lock(p: task);
433 retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
434 task_unlock(p: task);
435 if (retval)
436 goto unlock_creds;
437
438 write_lock_irq(&tasklist_lock);
439 retval = -EPERM;
440 if (unlikely(task->exit_state))
441 goto unlock_tasklist;
442 if (task->ptrace)
443 goto unlock_tasklist;
444
445 task->ptrace = flags;
446
447 ptrace_link(child: task, current);
448
449 /* SEIZE doesn't trap tracee on attach */
450 if (!seize)
451 send_sig_info(SIGSTOP, SEND_SIG_PRIV, task);
452
453 spin_lock(lock: &task->sighand->siglock);
454
455 /*
456 * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
457 * TRAPPING, and kick it so that it transits to TRACED. TRAPPING
458 * will be cleared if the child completes the transition or any
459 * event which clears the group stop states happens. We'll wait
460 * for the transition to complete before returning from this
461 * function.
462 *
463 * This hides STOPPED -> RUNNING -> TRACED transition from the
464 * attaching thread but a different thread in the same group can
465 * still observe the transient RUNNING state. IOW, if another
466 * thread's WNOHANG wait(2) on the stopped tracee races against
467 * ATTACH, the wait(2) may fail due to the transient RUNNING.
468 *
469 * The following task_is_stopped() test is safe as both transitions
470 * in and out of STOPPED are protected by siglock.
471 */
472 if (task_is_stopped(task) &&
473 task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) {
474 task->jobctl &= ~JOBCTL_STOPPED;
475 signal_wake_up_state(t: task, __TASK_STOPPED);
476 }
477
478 spin_unlock(lock: &task->sighand->siglock);
479
480 retval = 0;
481unlock_tasklist:
482 write_unlock_irq(&tasklist_lock);
483unlock_creds:
484 mutex_unlock(lock: &task->signal->cred_guard_mutex);
485out:
486 if (!retval) {
487 /*
488 * We do not bother to change retval or clear JOBCTL_TRAPPING
489 * if wait_on_bit() was interrupted by SIGKILL. The tracer will
490 * not return to user-mode, it will exit and clear this bit in
491 * __ptrace_unlink() if it wasn't already cleared by the tracee;
492 * and until then nobody can ptrace this task.
493 */
494 wait_on_bit(word: &task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE);
495 proc_ptrace_connector(task, PTRACE_ATTACH);
496 }
497
498 return retval;
499}
500
501/**
502 * ptrace_traceme -- helper for PTRACE_TRACEME
503 *
504 * Performs checks and sets PT_PTRACED.
505 * Should be used by all ptrace implementations for PTRACE_TRACEME.
506 */
507static int ptrace_traceme(void)
508{
509 int ret = -EPERM;
510
511 write_lock_irq(&tasklist_lock);
512 /* Are we already being traced? */
513 if (!current->ptrace) {
514 ret = security_ptrace_traceme(current->parent);
515 /*
516 * Check PF_EXITING to ensure ->real_parent has not passed
517 * exit_ptrace(). Otherwise we don't report the error but
518 * pretend ->real_parent untraces us right after return.
519 */
520 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
521 current->ptrace = PT_PTRACED;
522 ptrace_link(current, current->real_parent);
523 }
524 }
525 write_unlock_irq(&tasklist_lock);
526
527 return ret;
528}
529
530/*
531 * Called with irqs disabled, returns true if childs should reap themselves.
532 */
533static int ignoring_children(struct sighand_struct *sigh)
534{
535 int ret;
536 spin_lock(lock: &sigh->siglock);
537 ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
538 (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
539 spin_unlock(lock: &sigh->siglock);
540 return ret;
541}
542
543/*
544 * Called with tasklist_lock held for writing.
545 * Unlink a traced task, and clean it up if it was a traced zombie.
546 * Return true if it needs to be reaped with release_task().
547 * (We can't call release_task() here because we already hold tasklist_lock.)
548 *
549 * If it's a zombie, our attachedness prevented normal parent notification
550 * or self-reaping. Do notification now if it would have happened earlier.
551 * If it should reap itself, return true.
552 *
553 * If it's our own child, there is no notification to do. But if our normal
554 * children self-reap, then this child was prevented by ptrace and we must
555 * reap it now, in that case we must also wake up sub-threads sleeping in
556 * do_wait().
557 */
558static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
559{
560 bool dead;
561
562 __ptrace_unlink(child: p);
563
564 if (p->exit_state != EXIT_ZOMBIE)
565 return false;
566
567 dead = !thread_group_leader(p);
568
569 if (!dead && thread_group_empty(p)) {
570 if (!same_thread_group(p1: p->real_parent, p2: tracer))
571 dead = do_notify_parent(p, p->exit_signal);
572 else if (ignoring_children(sigh: tracer->sighand)) {
573 __wake_up_parent(p, parent: tracer);
574 dead = true;
575 }
576 }
577 /* Mark it as in the process of being reaped. */
578 if (dead)
579 p->exit_state = EXIT_DEAD;
580 return dead;
581}
582
583static int ptrace_detach(struct task_struct *child, unsigned int data)
584{
585 if (!valid_signal(sig: data))
586 return -EIO;
587
588 /* Architecture-specific hardware disable .. */
589 ptrace_disable(child);
590
591 write_lock_irq(&tasklist_lock);
592 /*
593 * We rely on ptrace_freeze_traced(). It can't be killed and
594 * untraced by another thread, it can't be a zombie.
595 */
596 WARN_ON(!child->ptrace || child->exit_state);
597 /*
598 * tasklist_lock avoids the race with wait_task_stopped(), see
599 * the comment in ptrace_resume().
600 */
601 child->exit_code = data;
602 __ptrace_detach(current, p: child);
603 write_unlock_irq(&tasklist_lock);
604
605 proc_ptrace_connector(task: child, PTRACE_DETACH);
606
607 return 0;
608}
609
610/*
611 * Detach all tasks we were using ptrace on. Called with tasklist held
612 * for writing.
613 */
614void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
615{
616 struct task_struct *p, *n;
617
618 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
619 if (unlikely(p->ptrace & PT_EXITKILL))
620 send_sig_info(SIGKILL, SEND_SIG_PRIV, p);
621
622 if (__ptrace_detach(tracer, p))
623 list_add(new: &p->ptrace_entry, head: dead);
624 }
625}
626
627int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
628{
629 int copied = 0;
630
631 while (len > 0) {
632 char buf[128];
633 int this_len, retval;
634
635 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
636 retval = ptrace_access_vm(tsk, addr: src, buf, len: this_len, gup_flags: FOLL_FORCE);
637
638 if (!retval) {
639 if (copied)
640 break;
641 return -EIO;
642 }
643 if (copy_to_user(to: dst, from: buf, n: retval))
644 return -EFAULT;
645 copied += retval;
646 src += retval;
647 dst += retval;
648 len -= retval;
649 }
650 return copied;
651}
652
653int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
654{
655 int copied = 0;
656
657 while (len > 0) {
658 char buf[128];
659 int this_len, retval;
660
661 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
662 if (copy_from_user(to: buf, from: src, n: this_len))
663 return -EFAULT;
664 retval = ptrace_access_vm(tsk, addr: dst, buf, len: this_len,
665 gup_flags: FOLL_FORCE | FOLL_WRITE);
666 if (!retval) {
667 if (copied)
668 break;
669 return -EIO;
670 }
671 copied += retval;
672 src += retval;
673 dst += retval;
674 len -= retval;
675 }
676 return copied;
677}
678
679static int ptrace_setoptions(struct task_struct *child, unsigned long data)
680{
681 unsigned flags;
682 int ret;
683
684 ret = check_ptrace_options(data);
685 if (ret)
686 return ret;
687
688 /* Avoid intermediate state when all opts are cleared */
689 flags = child->ptrace;
690 flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
691 flags |= (data << PT_OPT_FLAG_SHIFT);
692 child->ptrace = flags;
693
694 return 0;
695}
696
697static int ptrace_getsiginfo(struct task_struct *child, kernel_siginfo_t *info)
698{
699 unsigned long flags;
700 int error = -ESRCH;
701
702 if (lock_task_sighand(task: child, flags: &flags)) {
703 error = -EINVAL;
704 if (likely(child->last_siginfo != NULL)) {
705 copy_siginfo(to: info, from: child->last_siginfo);
706 error = 0;
707 }
708 unlock_task_sighand(task: child, flags: &flags);
709 }
710 return error;
711}
712
713static int ptrace_setsiginfo(struct task_struct *child, const kernel_siginfo_t *info)
714{
715 unsigned long flags;
716 int error = -ESRCH;
717
718 if (lock_task_sighand(task: child, flags: &flags)) {
719 error = -EINVAL;
720 if (likely(child->last_siginfo != NULL)) {
721 copy_siginfo(to: child->last_siginfo, from: info);
722 error = 0;
723 }
724 unlock_task_sighand(task: child, flags: &flags);
725 }
726 return error;
727}
728
729static int ptrace_peek_siginfo(struct task_struct *child,
730 unsigned long addr,
731 unsigned long data)
732{
733 struct ptrace_peeksiginfo_args arg;
734 struct sigpending *pending;
735 struct sigqueue *q;
736 int ret, i;
737
738 ret = copy_from_user(to: &arg, from: (void __user *) addr,
739 n: sizeof(struct ptrace_peeksiginfo_args));
740 if (ret)
741 return -EFAULT;
742
743 if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
744 return -EINVAL; /* unknown flags */
745
746 if (arg.nr < 0)
747 return -EINVAL;
748
749 /* Ensure arg.off fits in an unsigned long */
750 if (arg.off > ULONG_MAX)
751 return 0;
752
753 if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
754 pending = &child->signal->shared_pending;
755 else
756 pending = &child->pending;
757
758 for (i = 0; i < arg.nr; ) {
759 kernel_siginfo_t info;
760 unsigned long off = arg.off + i;
761 bool found = false;
762
763 spin_lock_irq(lock: &child->sighand->siglock);
764 list_for_each_entry(q, &pending->list, list) {
765 if (!off--) {
766 found = true;
767 copy_siginfo(to: &info, from: &q->info);
768 break;
769 }
770 }
771 spin_unlock_irq(lock: &child->sighand->siglock);
772
773 if (!found) /* beyond the end of the list */
774 break;
775
776#ifdef CONFIG_COMPAT
777 if (unlikely(in_compat_syscall())) {
778 compat_siginfo_t __user *uinfo = compat_ptr(uptr: data);
779
780 if (copy_siginfo_to_user32(to: uinfo, from: &info)) {
781 ret = -EFAULT;
782 break;
783 }
784
785 } else
786#endif
787 {
788 siginfo_t __user *uinfo = (siginfo_t __user *) data;
789
790 if (copy_siginfo_to_user(to: uinfo, from: &info)) {
791 ret = -EFAULT;
792 break;
793 }
794 }
795
796 data += sizeof(siginfo_t);
797 i++;
798
799 if (signal_pending(current))
800 break;
801
802 cond_resched();
803 }
804
805 if (i > 0)
806 return i;
807
808 return ret;
809}
810
811#ifdef CONFIG_RSEQ
812static long ptrace_get_rseq_configuration(struct task_struct *task,
813 unsigned long size, void __user *data)
814{
815 struct ptrace_rseq_configuration conf = {
816 .rseq_abi_pointer = (u64)(uintptr_t)task->rseq,
817 .rseq_abi_size = task->rseq_len,
818 .signature = task->rseq_sig,
819 .flags = 0,
820 };
821
822 size = min_t(unsigned long, size, sizeof(conf));
823 if (copy_to_user(to: data, from: &conf, n: size))
824 return -EFAULT;
825 return sizeof(conf);
826}
827#endif
828
829#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
830
831#ifdef PTRACE_SINGLEBLOCK
832#define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
833#else
834#define is_singleblock(request) 0
835#endif
836
837#ifdef PTRACE_SYSEMU
838#define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
839#else
840#define is_sysemu_singlestep(request) 0
841#endif
842
843static int ptrace_resume(struct task_struct *child, long request,
844 unsigned long data)
845{
846 if (!valid_signal(sig: data))
847 return -EIO;
848
849 if (request == PTRACE_SYSCALL)
850 set_task_syscall_work(child, SYSCALL_TRACE);
851 else
852 clear_task_syscall_work(child, SYSCALL_TRACE);
853
854#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
855 if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
856 set_task_syscall_work(child, SYSCALL_EMU);
857 else
858 clear_task_syscall_work(child, SYSCALL_EMU);
859#endif
860
861 if (is_singleblock(request)) {
862 if (unlikely(!arch_has_block_step()))
863 return -EIO;
864 user_enable_block_step(child);
865 } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
866 if (unlikely(!arch_has_single_step()))
867 return -EIO;
868 user_enable_single_step(child);
869 } else {
870 user_disable_single_step(child);
871 }
872
873 /*
874 * Change ->exit_code and ->state under siglock to avoid the race
875 * with wait_task_stopped() in between; a non-zero ->exit_code will
876 * wrongly look like another report from tracee.
877 *
878 * Note that we need siglock even if ->exit_code == data and/or this
879 * status was not reported yet, the new status must not be cleared by
880 * wait_task_stopped() after resume.
881 */
882 spin_lock_irq(lock: &child->sighand->siglock);
883 child->exit_code = data;
884 child->jobctl &= ~JOBCTL_TRACED;
885 wake_up_state(tsk: child, __TASK_TRACED);
886 spin_unlock_irq(lock: &child->sighand->siglock);
887
888 return 0;
889}
890
891#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
892
893static const struct user_regset *
894find_regset(const struct user_regset_view *view, unsigned int type)
895{
896 const struct user_regset *regset;
897 int n;
898
899 for (n = 0; n < view->n; ++n) {
900 regset = view->regsets + n;
901 if (regset->core_note_type == type)
902 return regset;
903 }
904
905 return NULL;
906}
907
908static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
909 struct iovec *kiov)
910{
911 const struct user_regset_view *view = task_user_regset_view(tsk: task);
912 const struct user_regset *regset = find_regset(view, type);
913 int regset_no;
914
915 if (!regset || (kiov->iov_len % regset->size) != 0)
916 return -EINVAL;
917
918 regset_no = regset - view->regsets;
919 kiov->iov_len = min(kiov->iov_len,
920 (__kernel_size_t) (regset->n * regset->size));
921
922 if (req == PTRACE_GETREGSET)
923 return copy_regset_to_user(target: task, view, setno: regset_no, offset: 0,
924 size: kiov->iov_len, data: kiov->iov_base);
925 else
926 return copy_regset_from_user(target: task, view, setno: regset_no, offset: 0,
927 size: kiov->iov_len, data: kiov->iov_base);
928}
929
930/*
931 * This is declared in linux/regset.h and defined in machine-dependent
932 * code. We put the export here, near the primary machine-neutral use,
933 * to ensure no machine forgets it.
934 */
935EXPORT_SYMBOL_GPL(task_user_regset_view);
936
937static unsigned long
938ptrace_get_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
939 struct ptrace_syscall_info *info)
940{
941 unsigned long args[ARRAY_SIZE(info->entry.args)];
942 int i;
943
944 info->op = PTRACE_SYSCALL_INFO_ENTRY;
945 info->entry.nr = syscall_get_nr(task: child, regs);
946 syscall_get_arguments(task: child, regs, args);
947 for (i = 0; i < ARRAY_SIZE(args); i++)
948 info->entry.args[i] = args[i];
949
950 /* args is the last field in struct ptrace_syscall_info.entry */
951 return offsetofend(struct ptrace_syscall_info, entry.args);
952}
953
954static unsigned long
955ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
956 struct ptrace_syscall_info *info)
957{
958 /*
959 * As struct ptrace_syscall_info.entry is currently a subset
960 * of struct ptrace_syscall_info.seccomp, it makes sense to
961 * initialize that subset using ptrace_get_syscall_info_entry().
962 * This can be reconsidered in the future if these structures
963 * diverge significantly enough.
964 */
965 ptrace_get_syscall_info_entry(child, regs, info);
966 info->op = PTRACE_SYSCALL_INFO_SECCOMP;
967 info->seccomp.ret_data = child->ptrace_message;
968
969 /* ret_data is the last field in struct ptrace_syscall_info.seccomp */
970 return offsetofend(struct ptrace_syscall_info, seccomp.ret_data);
971}
972
973static unsigned long
974ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
975 struct ptrace_syscall_info *info)
976{
977 info->op = PTRACE_SYSCALL_INFO_EXIT;
978 info->exit.rval = syscall_get_error(task: child, regs);
979 info->exit.is_error = !!info->exit.rval;
980 if (!info->exit.is_error)
981 info->exit.rval = syscall_get_return_value(task: child, regs);
982
983 /* is_error is the last field in struct ptrace_syscall_info.exit */
984 return offsetofend(struct ptrace_syscall_info, exit.is_error);
985}
986
987static int
988ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
989 void __user *datavp)
990{
991 struct pt_regs *regs = task_pt_regs(child);
992 struct ptrace_syscall_info info = {
993 .op = PTRACE_SYSCALL_INFO_NONE,
994 .arch = syscall_get_arch(task: child),
995 .instruction_pointer = instruction_pointer(regs),
996 .stack_pointer = user_stack_pointer(regs),
997 };
998 unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
999 unsigned long write_size;
1000
1001 /*
1002 * This does not need lock_task_sighand() to access
1003 * child->last_siginfo because ptrace_freeze_traced()
1004 * called earlier by ptrace_check_attach() ensures that
1005 * the tracee cannot go away and clear its last_siginfo.
1006 */
1007 switch (child->last_siginfo ? child->last_siginfo->si_code : 0) {
1008 case SIGTRAP | 0x80:
1009 switch (child->ptrace_message) {
1010 case PTRACE_EVENTMSG_SYSCALL_ENTRY:
1011 actual_size = ptrace_get_syscall_info_entry(child, regs,
1012 info: &info);
1013 break;
1014 case PTRACE_EVENTMSG_SYSCALL_EXIT:
1015 actual_size = ptrace_get_syscall_info_exit(child, regs,
1016 info: &info);
1017 break;
1018 }
1019 break;
1020 case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8):
1021 actual_size = ptrace_get_syscall_info_seccomp(child, regs,
1022 info: &info);
1023 break;
1024 }
1025
1026 write_size = min(actual_size, user_size);
1027 return copy_to_user(to: datavp, from: &info, n: write_size) ? -EFAULT : actual_size;
1028}
1029#endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
1030
1031int ptrace_request(struct task_struct *child, long request,
1032 unsigned long addr, unsigned long data)
1033{
1034 bool seized = child->ptrace & PT_SEIZED;
1035 int ret = -EIO;
1036 kernel_siginfo_t siginfo, *si;
1037 void __user *datavp = (void __user *) data;
1038 unsigned long __user *datalp = datavp;
1039 unsigned long flags;
1040
1041 switch (request) {
1042 case PTRACE_PEEKTEXT:
1043 case PTRACE_PEEKDATA:
1044 return generic_ptrace_peekdata(tsk: child, addr, data);
1045 case PTRACE_POKETEXT:
1046 case PTRACE_POKEDATA:
1047 return generic_ptrace_pokedata(tsk: child, addr, data);
1048
1049#ifdef PTRACE_OLDSETOPTIONS
1050 case PTRACE_OLDSETOPTIONS:
1051#endif
1052 case PTRACE_SETOPTIONS:
1053 ret = ptrace_setoptions(child, data);
1054 break;
1055 case PTRACE_GETEVENTMSG:
1056 ret = put_user(child->ptrace_message, datalp);
1057 break;
1058
1059 case PTRACE_PEEKSIGINFO:
1060 ret = ptrace_peek_siginfo(child, addr, data);
1061 break;
1062
1063 case PTRACE_GETSIGINFO:
1064 ret = ptrace_getsiginfo(child, info: &siginfo);
1065 if (!ret)
1066 ret = copy_siginfo_to_user(to: datavp, from: &siginfo);
1067 break;
1068
1069 case PTRACE_SETSIGINFO:
1070 ret = copy_siginfo_from_user(to: &siginfo, from: datavp);
1071 if (!ret)
1072 ret = ptrace_setsiginfo(child, info: &siginfo);
1073 break;
1074
1075 case PTRACE_GETSIGMASK: {
1076 sigset_t *mask;
1077
1078 if (addr != sizeof(sigset_t)) {
1079 ret = -EINVAL;
1080 break;
1081 }
1082
1083 if (test_tsk_restore_sigmask(task: child))
1084 mask = &child->saved_sigmask;
1085 else
1086 mask = &child->blocked;
1087
1088 if (copy_to_user(to: datavp, from: mask, n: sizeof(sigset_t)))
1089 ret = -EFAULT;
1090 else
1091 ret = 0;
1092
1093 break;
1094 }
1095
1096 case PTRACE_SETSIGMASK: {
1097 sigset_t new_set;
1098
1099 if (addr != sizeof(sigset_t)) {
1100 ret = -EINVAL;
1101 break;
1102 }
1103
1104 if (copy_from_user(to: &new_set, from: datavp, n: sizeof(sigset_t))) {
1105 ret = -EFAULT;
1106 break;
1107 }
1108
1109 sigdelsetmask(set: &new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1110
1111 /*
1112 * Every thread does recalc_sigpending() after resume, so
1113 * retarget_shared_pending() and recalc_sigpending() are not
1114 * called here.
1115 */
1116 spin_lock_irq(lock: &child->sighand->siglock);
1117 child->blocked = new_set;
1118 spin_unlock_irq(lock: &child->sighand->siglock);
1119
1120 clear_tsk_restore_sigmask(task: child);
1121
1122 ret = 0;
1123 break;
1124 }
1125
1126 case PTRACE_INTERRUPT:
1127 /*
1128 * Stop tracee without any side-effect on signal or job
1129 * control. At least one trap is guaranteed to happen
1130 * after this request. If @child is already trapped, the
1131 * current trap is not disturbed and another trap will
1132 * happen after the current trap is ended with PTRACE_CONT.
1133 *
1134 * The actual trap might not be PTRACE_EVENT_STOP trap but
1135 * the pending condition is cleared regardless.
1136 */
1137 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
1138 break;
1139
1140 /*
1141 * INTERRUPT doesn't disturb existing trap sans one
1142 * exception. If ptracer issued LISTEN for the current
1143 * STOP, this INTERRUPT should clear LISTEN and re-trap
1144 * tracee into STOP.
1145 */
1146 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
1147 ptrace_signal_wake_up(t: child, resume: child->jobctl & JOBCTL_LISTENING);
1148
1149 unlock_task_sighand(task: child, flags: &flags);
1150 ret = 0;
1151 break;
1152
1153 case PTRACE_LISTEN:
1154 /*
1155 * Listen for events. Tracee must be in STOP. It's not
1156 * resumed per-se but is not considered to be in TRACED by
1157 * wait(2) or ptrace(2). If an async event (e.g. group
1158 * stop state change) happens, tracee will enter STOP trap
1159 * again. Alternatively, ptracer can issue INTERRUPT to
1160 * finish listening and re-trap tracee into STOP.
1161 */
1162 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
1163 break;
1164
1165 si = child->last_siginfo;
1166 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
1167 child->jobctl |= JOBCTL_LISTENING;
1168 /*
1169 * If NOTIFY is set, it means event happened between
1170 * start of this trap and now. Trigger re-trap.
1171 */
1172 if (child->jobctl & JOBCTL_TRAP_NOTIFY)
1173 ptrace_signal_wake_up(t: child, resume: true);
1174 ret = 0;
1175 }
1176 unlock_task_sighand(task: child, flags: &flags);
1177 break;
1178
1179 case PTRACE_DETACH: /* detach a process that was attached. */
1180 ret = ptrace_detach(child, data);
1181 break;
1182
1183#ifdef CONFIG_BINFMT_ELF_FDPIC
1184 case PTRACE_GETFDPIC: {
1185 struct mm_struct *mm = get_task_mm(child);
1186 unsigned long tmp = 0;
1187
1188 ret = -ESRCH;
1189 if (!mm)
1190 break;
1191
1192 switch (addr) {
1193 case PTRACE_GETFDPIC_EXEC:
1194 tmp = mm->context.exec_fdpic_loadmap;
1195 break;
1196 case PTRACE_GETFDPIC_INTERP:
1197 tmp = mm->context.interp_fdpic_loadmap;
1198 break;
1199 default:
1200 break;
1201 }
1202 mmput(mm);
1203
1204 ret = put_user(tmp, datalp);
1205 break;
1206 }
1207#endif
1208
1209 case PTRACE_SINGLESTEP:
1210#ifdef PTRACE_SINGLEBLOCK
1211 case PTRACE_SINGLEBLOCK:
1212#endif
1213#ifdef PTRACE_SYSEMU
1214 case PTRACE_SYSEMU:
1215 case PTRACE_SYSEMU_SINGLESTEP:
1216#endif
1217 case PTRACE_SYSCALL:
1218 case PTRACE_CONT:
1219 return ptrace_resume(child, request, data);
1220
1221 case PTRACE_KILL:
1222 send_sig_info(SIGKILL, SEND_SIG_NOINFO, child);
1223 return 0;
1224
1225#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1226 case PTRACE_GETREGSET:
1227 case PTRACE_SETREGSET: {
1228 struct iovec kiov;
1229 struct iovec __user *uiov = datavp;
1230
1231 if (!access_ok(uiov, sizeof(*uiov)))
1232 return -EFAULT;
1233
1234 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1235 __get_user(kiov.iov_len, &uiov->iov_len))
1236 return -EFAULT;
1237
1238 ret = ptrace_regset(task: child, req: request, type: addr, kiov: &kiov);
1239 if (!ret)
1240 ret = __put_user(kiov.iov_len, &uiov->iov_len);
1241 break;
1242 }
1243
1244 case PTRACE_GET_SYSCALL_INFO:
1245 ret = ptrace_get_syscall_info(child, user_size: addr, datavp);
1246 break;
1247#endif
1248
1249 case PTRACE_SECCOMP_GET_FILTER:
1250 ret = seccomp_get_filter(task: child, filter_off: addr, data: datavp);
1251 break;
1252
1253 case PTRACE_SECCOMP_GET_METADATA:
1254 ret = seccomp_get_metadata(task: child, filter_off: addr, data: datavp);
1255 break;
1256
1257#ifdef CONFIG_RSEQ
1258 case PTRACE_GET_RSEQ_CONFIGURATION:
1259 ret = ptrace_get_rseq_configuration(task: child, size: addr, data: datavp);
1260 break;
1261#endif
1262
1263 case PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG:
1264 ret = syscall_user_dispatch_set_config(task: child, size: addr, data: datavp);
1265 break;
1266
1267 case PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG:
1268 ret = syscall_user_dispatch_get_config(task: child, size: addr, data: datavp);
1269 break;
1270
1271 default:
1272 break;
1273 }
1274
1275 return ret;
1276}
1277
1278SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1279 unsigned long, data)
1280{
1281 struct task_struct *child;
1282 long ret;
1283
1284 if (request == PTRACE_TRACEME) {
1285 ret = ptrace_traceme();
1286 goto out;
1287 }
1288
1289 child = find_get_task_by_vpid(nr: pid);
1290 if (!child) {
1291 ret = -ESRCH;
1292 goto out;
1293 }
1294
1295 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1296 ret = ptrace_attach(task: child, request, addr, flags: data);
1297 goto out_put_task_struct;
1298 }
1299
1300 ret = ptrace_check_attach(child, ignore_state: request == PTRACE_KILL ||
1301 request == PTRACE_INTERRUPT);
1302 if (ret < 0)
1303 goto out_put_task_struct;
1304
1305 ret = arch_ptrace(child, request, addr, data);
1306 if (ret || request != PTRACE_DETACH)
1307 ptrace_unfreeze_traced(task: child);
1308
1309 out_put_task_struct:
1310 put_task_struct(t: child);
1311 out:
1312 return ret;
1313}
1314
1315int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1316 unsigned long data)
1317{
1318 unsigned long tmp;
1319 int copied;
1320
1321 copied = ptrace_access_vm(tsk, addr, buf: &tmp, len: sizeof(tmp), gup_flags: FOLL_FORCE);
1322 if (copied != sizeof(tmp))
1323 return -EIO;
1324 return put_user(tmp, (unsigned long __user *)data);
1325}
1326
1327int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1328 unsigned long data)
1329{
1330 int copied;
1331
1332 copied = ptrace_access_vm(tsk, addr, buf: &data, len: sizeof(data),
1333 gup_flags: FOLL_FORCE | FOLL_WRITE);
1334 return (copied == sizeof(data)) ? 0 : -EIO;
1335}
1336
1337#if defined CONFIG_COMPAT
1338
1339int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1340 compat_ulong_t addr, compat_ulong_t data)
1341{
1342 compat_ulong_t __user *datap = compat_ptr(uptr: data);
1343 compat_ulong_t word;
1344 kernel_siginfo_t siginfo;
1345 int ret;
1346
1347 switch (request) {
1348 case PTRACE_PEEKTEXT:
1349 case PTRACE_PEEKDATA:
1350 ret = ptrace_access_vm(tsk: child, addr, buf: &word, len: sizeof(word),
1351 gup_flags: FOLL_FORCE);
1352 if (ret != sizeof(word))
1353 ret = -EIO;
1354 else
1355 ret = put_user(word, datap);
1356 break;
1357
1358 case PTRACE_POKETEXT:
1359 case PTRACE_POKEDATA:
1360 ret = ptrace_access_vm(tsk: child, addr, buf: &data, len: sizeof(data),
1361 gup_flags: FOLL_FORCE | FOLL_WRITE);
1362 ret = (ret != sizeof(data) ? -EIO : 0);
1363 break;
1364
1365 case PTRACE_GETEVENTMSG:
1366 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1367 break;
1368
1369 case PTRACE_GETSIGINFO:
1370 ret = ptrace_getsiginfo(child, info: &siginfo);
1371 if (!ret)
1372 ret = copy_siginfo_to_user32(
1373 to: (struct compat_siginfo __user *) datap,
1374 from: &siginfo);
1375 break;
1376
1377 case PTRACE_SETSIGINFO:
1378 ret = copy_siginfo_from_user32(
1379 to: &siginfo, from: (struct compat_siginfo __user *) datap);
1380 if (!ret)
1381 ret = ptrace_setsiginfo(child, info: &siginfo);
1382 break;
1383#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1384 case PTRACE_GETREGSET:
1385 case PTRACE_SETREGSET:
1386 {
1387 struct iovec kiov;
1388 struct compat_iovec __user *uiov =
1389 (struct compat_iovec __user *) datap;
1390 compat_uptr_t ptr;
1391 compat_size_t len;
1392
1393 if (!access_ok(uiov, sizeof(*uiov)))
1394 return -EFAULT;
1395
1396 if (__get_user(ptr, &uiov->iov_base) ||
1397 __get_user(len, &uiov->iov_len))
1398 return -EFAULT;
1399
1400 kiov.iov_base = compat_ptr(uptr: ptr);
1401 kiov.iov_len = len;
1402
1403 ret = ptrace_regset(task: child, req: request, type: addr, kiov: &kiov);
1404 if (!ret)
1405 ret = __put_user(kiov.iov_len, &uiov->iov_len);
1406 break;
1407 }
1408#endif
1409
1410 default:
1411 ret = ptrace_request(child, request, addr, data);
1412 }
1413
1414 return ret;
1415}
1416
1417COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1418 compat_long_t, addr, compat_long_t, data)
1419{
1420 struct task_struct *child;
1421 long ret;
1422
1423 if (request == PTRACE_TRACEME) {
1424 ret = ptrace_traceme();
1425 goto out;
1426 }
1427
1428 child = find_get_task_by_vpid(nr: pid);
1429 if (!child) {
1430 ret = -ESRCH;
1431 goto out;
1432 }
1433
1434 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1435 ret = ptrace_attach(task: child, request, addr, flags: data);
1436 goto out_put_task_struct;
1437 }
1438
1439 ret = ptrace_check_attach(child, ignore_state: request == PTRACE_KILL ||
1440 request == PTRACE_INTERRUPT);
1441 if (!ret) {
1442 ret = compat_arch_ptrace(child, request, addr, data);
1443 if (ret || request != PTRACE_DETACH)
1444 ptrace_unfreeze_traced(task: child);
1445 }
1446
1447 out_put_task_struct:
1448 put_task_struct(t: child);
1449 out:
1450 return ret;
1451}
1452#endif /* CONFIG_COMPAT */
1453

source code of linux/kernel/ptrace.c