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* linux/kernel/ptrace.c

* Common interfaces for "ptrace()" which we do not want

* to continually duplicate across every architecture.

#include <linux/capability.h>

#include <linux/export.h>

#include <linux/sched.h>

#include <linux/errno.h>

#include <linux/mm.h>

#include <linux/highmem.h>

#include <linux/pagemap.h>

#include <linux/ptrace.h>

#include <linux/security.h>

#include <linux/signal.h>

#include <linux/uio.h>

#include <linux/audit.h>

#include <linux/pid_namespace.h>

#include <linux/syscalls.h>

#include <linux/uaccess.h>

#include <linux/regset.h>

#include <linux/hw_breakpoint.h>

#include <linux/cn_proc.h>

#include <linux/compat.h>

static int ptrace_trapping_sleep_fn(void *flags)

{

schedule();

return 0;

}

* ptrace a task: make the debugger its new parent and

* move it to the ptrace list.

* Must be called with the tasklist lock write-held.

void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)

{

BUG_ON(!list_empty(&child->ptrace_entry));

list_add(&child->ptrace_entry, &new_parent->ptraced);

child->parent = new_parent;

}

/**

* __ptrace_unlink - unlink ptracee and restore its execution state

* @child: ptracee to be unlinked

* Remove @child from the ptrace list, move it back to the original parent,

* and restore the execution state so that it conforms to the group stop

* state.

* Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer

* exiting. For PTRACE_DETACH, unless the ptracee has been killed between

* ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.

* If the ptracer is exiting, the ptracee can be in any state.

* After detach, the ptracee should be in a state which conforms to the

* group stop. If the group is stopped or in the process of stopping, the

* ptracee should be put into TASK_STOPPED; otherwise, it should be woken

* up from TASK_TRACED.

* If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,

* it goes through TRACED -> RUNNING -> STOPPED transition which is similar

* to but in the opposite direction of what happens while attaching to a

* stopped task. However, in this direction, the intermediate RUNNING

* state is not hidden even from the current ptracer and if it immediately

* re-attaches and performs a WNOHANG wait(2), it may fail.

* CONTEXT:

* write_lock_irq(tasklist_lock)

void __ptrace_unlink(struct task_struct *child)

{

BUG_ON(!child->ptrace);

child->ptrace = 0;

child->parent = child->real_parent;

list_del_init(&child->ptrace_entry);

spin_lock(&child->sighand->siglock);

* Clear all pending traps and TRAPPING. TRAPPING should be

* cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly.

task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);

task_clear_jobctl_trapping(child);

* Reinstate JOBCTL_STOP_PENDING if group stop is in effect and

* @child isn't dead.

if (!(child->flags & PF_EXITING) &&

(child->signal->flags & SIGNAL_STOP_STOPPED ||

child->signal->group_stop_count)) {

child->jobctl |= JOBCTL_STOP_PENDING;

* This is only possible if this thread was cloned by the

* traced task running in the stopped group, set the signal

* for the future reports.

* FIXME: we should change ptrace_init_task() to handle this

* case.

if (!(child->jobctl & JOBCTL_STOP_SIGMASK))

child->jobctl |= SIGSTOP;

}

* If transition to TASK_STOPPED is pending or in TASK_TRACED, kick

* @child in the butt. Note that @resume should be used iff @child

* is in TASK_TRACED; otherwise, we might unduly disrupt

* TASK_KILLABLE sleeps.

if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))

ptrace_signal_wake_up(child, true);

spin_unlock(&child->sighand->siglock);

}

/* Ensure that nothing can wake it up, even SIGKILL */

static bool ptrace_freeze_traced(struct task_struct *task)

{

bool ret = false;

/* Lockless, nobody but us can set this flag */

if (task->jobctl & JOBCTL_LISTENING)

return ret;

spin_lock_irq(&task->sighand->siglock);

if (task_is_traced(task) && !__fatal_signal_pending(task)) {

task->state = __TASK_TRACED;

ret = true;

}

spin_unlock_irq(&task->sighand->siglock);

return ret;

}

static void ptrace_unfreeze_traced(struct task_struct *task)

{

if (task->state != __TASK_TRACED)

return;

WARN_ON(!task->ptrace || task->parent != current);

spin_lock_irq(&task->sighand->siglock);

if (__fatal_signal_pending(task))

wake_up_state(task, __TASK_TRACED);

else

task->state = TASK_TRACED;

spin_unlock_irq(&task->sighand->siglock);

}

/**

* ptrace_check_attach - check whether ptracee is ready for ptrace operation

* @child: ptracee to check for

* @ignore_state: don't check whether @child is currently %TASK_TRACED

* Check whether @child is being ptraced by %current and ready for further

* ptrace operations. If @ignore_state is %false, @child also should be in

* %TASK_TRACED state and on return the child is guaranteed to be traced

* and not executing. If @ignore_state is %true, @child can be in any

* state.

* CONTEXT:

* Grabs and releases tasklist_lock and @child->sighand->siglock.

* RETURNS:

* 0 on success, -ESRCH if %child is not ready.

static int ptrace_check_attach(struct task_struct *child, bool ignore_state)

{

int ret = -ESRCH;

* We take the read lock around doing both checks to close a

* possible race where someone else was tracing our child and

* detached between these two checks. After this locked check,

* we are sure that this is our traced child and that can only

* be changed by us so it's not changing right after this.

read_lock(&tasklist_lock);

if (child->ptrace && child->parent == current) {

WARN_ON(child->state == __TASK_TRACED);

* child->sighand can't be NULL, release_task()

* does ptrace_unlink() before __exit_signal().

if (ignore_state || ptrace_freeze_traced(child))

ret = 0;

}

read_unlock(&tasklist_lock);

if (!ret && !ignore_state) {

if (!wait_task_inactive(child, __TASK_TRACED)) {

* This can only happen if may_ptrace_stop() fails and

* ptrace_stop() changes ->state back to TASK_RUNNING,

* so we should not worry about leaking __TASK_TRACED.

WARN_ON(child->state == __TASK_TRACED);

ret = -ESRCH;

}

return ret;

}

static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)

{

if (mode & PTRACE_MODE_NOAUDIT)

return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);

else

return has_ns_capability(current, ns, CAP_SYS_PTRACE);

}

/* Returns 0 on success, -errno on denial. */

static int __ptrace_may_access(struct task_struct *task, unsigned int mode)

{

const struct cred *cred = current_cred(), *tcred;

/* May we inspect the given task?

* This check is used both for attaching with ptrace

* and for allowing access to sensitive information in /proc.

* ptrace_attach denies several cases that /proc allows

* because setting up the necessary parent/child relationship

* or halting the specified task is impossible.

int dumpable = 0;

/* Don't let security modules deny introspection */

if (task == current)

return 0;

rcu_read_lock();

tcred = __task_cred(task);

if (uid_eq(cred->uid, tcred->euid) &&

uid_eq(cred->uid, tcred->suid) &&

uid_eq(cred->uid, tcred->uid) &&

gid_eq(cred->gid, tcred->egid) &&

gid_eq(cred->gid, tcred->sgid) &&

gid_eq(cred->gid, tcred->gid))

goto ok;

if (ptrace_has_cap(tcred->user_ns, mode))

goto ok;

rcu_read_unlock();

return -EPERM;

ok:

rcu_read_unlock();

smp_rmb();

if (task->mm)

dumpable = get_dumpable(task->mm);

rcu_read_lock();

if (!dumpable && !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {

rcu_read_unlock();

return -EPERM;

}

rcu_read_unlock();

return security_ptrace_access_check(task, mode);

}

bool ptrace_may_access(struct task_struct *task, unsigned int mode)

{

int err;

task_lock(task);

err = __ptrace_may_access(task, mode);

task_unlock(task);

return !err;

}

static int ptrace_attach(struct task_struct *task, long request,

unsigned long addr,

unsigned long flags)

{

bool seize = (request == PTRACE_SEIZE);

int retval;

retval = -EIO;

if (seize) {

if (addr != 0)

goto out;

if (flags & ~(unsigned long)PTRACE_O_MASK)

goto out;

flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);

} else {

flags = PT_PTRACED;

}

audit_ptrace(task);

retval = -EPERM;

if (unlikely(task->flags & PF_KTHREAD))

goto out;

if (same_thread_group(task, current))

goto out;

* Protect exec's credential calculations against our interference;

* SUID, SGID and LSM creds get determined differently

* under ptrace.

retval = -ERESTARTNOINTR;

if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))

goto out;

task_lock(task);

retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);

task_unlock(task);

if (retval)

goto unlock_creds;

write_lock_irq(&tasklist_lock);

retval = -EPERM;

if (unlikely(task->exit_state))

goto unlock_tasklist;

if (task->ptrace)

goto unlock_tasklist;

if (seize)

flags |= PT_SEIZED;

rcu_read_lock();

if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))

flags |= PT_PTRACE_CAP;

rcu_read_unlock();

task->ptrace = flags;

__ptrace_link(task, current);

/* SEIZE doesn't trap tracee on attach */

if (!seize)

send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);

spin_lock(&task->sighand->siglock);

* If the task is already STOPPED, set JOBCTL_TRAP_STOP and

* TRAPPING, and kick it so that it transits to TRACED. TRAPPING

* will be cleared if the child completes the transition or any

* event which clears the group stop states happens. We'll wait

* for the transition to complete before returning from this

* function.

* This hides STOPPED -> RUNNING -> TRACED transition from the

* attaching thread but a different thread in the same group can

* still observe the transient RUNNING state. IOW, if another

* thread's WNOHANG wait(2) on the stopped tracee races against

* ATTACH, the wait(2) may fail due to the transient RUNNING.

* The following task_is_stopped() test is safe as both transitions

* in and out of STOPPED are protected by siglock.

if (task_is_stopped(task) &&

task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))

signal_wake_up_state(task, __TASK_STOPPED);

spin_unlock(&task->sighand->siglock);

retval = 0;

unlock_tasklist:

write_unlock_irq(&tasklist_lock);

unlock_creds:

mutex_unlock(&task->signal->cred_guard_mutex);

out:

if (!retval) {

wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,

ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);

proc_ptrace_connector(task, PTRACE_ATTACH);

}

return retval;

}

/**

* ptrace_traceme -- helper for PTRACE_TRACEME

* Performs checks and sets PT_PTRACED.

* Should be used by all ptrace implementations for PTRACE_TRACEME.

static int ptrace_traceme(void)

{

int ret = -EPERM;

write_lock_irq(&tasklist_lock);

/* Are we already being traced? */

if (!current->ptrace) {

ret = security_ptrace_traceme(current->parent);

* Check PF_EXITING to ensure ->real_parent has not passed

* exit_ptrace(). Otherwise we don't report the error but

* pretend ->real_parent untraces us right after return.

if (!ret && !(current->real_parent->flags & PF_EXITING)) {

current->ptrace = PT_PTRACED;

__ptrace_link(current, current->real_parent);

}

write_unlock_irq(&tasklist_lock);

return ret;

}

* Called with irqs disabled, returns true if childs should reap themselves.

static int ignoring_children(struct sighand_struct *sigh)

{

int ret;

spin_lock(&sigh->siglock);

ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||

(sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);

spin_unlock(&sigh->siglock);

return ret;

}

* Called with tasklist_lock held for writing.

* Unlink a traced task, and clean it up if it was a traced zombie.

* Return true if it needs to be reaped with release_task().

* (We can't call release_task() here because we already hold tasklist_lock.)

* If it's a zombie, our attachedness prevented normal parent notification

* or self-reaping. Do notification now if it would have happened earlier.

* If it should reap itself, return true.

* If it's our own child, there is no notification to do. But if our normal

* children self-reap, then this child was prevented by ptrace and we must

* reap it now, in that case we must also wake up sub-threads sleeping in

* do_wait().

static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)

{

bool dead;

__ptrace_unlink(p);

if (p->exit_state != EXIT_ZOMBIE)

return false;

dead = !thread_group_leader(p);

if (!dead && thread_group_empty(p)) {

if (!same_thread_group(p->real_parent, tracer))

dead = do_notify_parent(p, p->exit_signal);

else if (ignoring_children(tracer->sighand)) {

__wake_up_parent(p, tracer);

dead = true;

}

/* Mark it as in the process of being reaped. */

if (dead)

p->exit_state = EXIT_DEAD;

return dead;

}

static int ptrace_detach(struct task_struct *child, unsigned int data)

{

bool dead = false;

if (!valid_signal(data))

return -EIO;

/* Architecture-specific hardware disable .. */

ptrace_disable(child);

clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

flush_ptrace_hw_breakpoint(child);

write_lock_irq(&tasklist_lock);

* This child can be already killed. Make sure de_thread() or

* our sub-thread doing do_wait() didn't do release_task() yet.

if (child->ptrace) {

child->exit_code = data;

dead = __ptrace_detach(current, child);

}

write_unlock_irq(&tasklist_lock);

proc_ptrace_connector(child, PTRACE_DETACH);

if (unlikely(dead))

release_task(child);

return 0;

}

* Detach all tasks we were using ptrace on. Called with tasklist held

* for writing, and returns with it held too. But note it can release

* and reacquire the lock.

void exit_ptrace(struct task_struct *tracer)

__releases(&tasklist_lock)

__acquires(&tasklist_lock)

{

struct task_struct *p, *n;

LIST_HEAD(ptrace_dead);

if (likely(list_empty(&tracer->ptraced)))

return;

list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {

if (unlikely(p->ptrace & PT_EXITKILL))

send_sig_info(SIGKILL, SEND_SIG_FORCED, p);

if (__ptrace_detach(tracer, p))

list_add(&p->ptrace_entry, &ptrace_dead);

}

write_unlock_irq(&tasklist_lock);

BUG_ON(!list_empty(&tracer->ptraced));

list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {

list_del_init(&p->ptrace_entry);

release_task(p);

}

write_lock_irq(&tasklist_lock);

}

int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)

{

int copied = 0;

while (len > 0) {

char buf[128];

int this_len, retval;

this_len = (len > sizeof(buf)) ? sizeof(buf) : len;

retval = access_process_vm(tsk, src, buf, this_len, 0);

if (!retval) {

if (copied)

break;

return -EIO;

}

if (copy_to_user(dst, buf, retval))

return -EFAULT;

copied += retval;

src += retval;

dst += retval;

len -= retval;

}

return copied;

}

int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)

{

int copied = 0;

while (len > 0) {

char buf[128];

int this_len, retval;

this_len = (len > sizeof(buf)) ? sizeof(buf) : len;

if (copy_from_user(buf, src, this_len))

return -EFAULT;

retval = access_process_vm(tsk, dst, buf, this_len, 1);

if (!retval) {

if (copied)

break;

return -EIO;

}

copied += retval;

src += retval;

dst += retval;

len -= retval;

}

return copied;

}

static int ptrace_setoptions(struct task_struct *child, unsigned long data)

{

unsigned flags;

if (data & ~(unsigned long)PTRACE_O_MASK)

return -EINVAL;

/* Avoid intermediate state when all opts are cleared */

flags = child->ptrace;

flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);

flags |= (data << PT_OPT_FLAG_SHIFT);

child->ptrace = flags;

return 0;

}

static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)

{

unsigned long flags;

int error = -ESRCH;

if (lock_task_sighand(child, &flags)) {

error = -EINVAL;

if (likely(child->last_siginfo != NULL)) {

*info = *child->last_siginfo;

error = 0;

}

unlock_task_sighand(child, &flags);

}

return error;

}

static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)

{

unsigned long flags;

int error = -ESRCH;

if (lock_task_sighand(child, &flags)) {

error = -EINVAL;

if (likely(child->last_siginfo != NULL)) {

*child->last_siginfo = *info;

error = 0;

}

unlock_task_sighand(child, &flags);

}

return error;

}

static int ptrace_peek_siginfo(struct task_struct *child,

unsigned long addr,

unsigned long data)

{

struct ptrace_peeksiginfo_args arg;

struct sigpending *pending;

struct sigqueue *q;

int ret, i;

ret = copy_from_user(&arg, (void __user *) addr,

sizeof(struct ptrace_peeksiginfo_args));

if (ret)

return -EFAULT;

if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)

return -EINVAL; /* unknown flags */

if (arg.nr < 0)

return -EINVAL;

if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)

pending = &child->signal->shared_pending;

else

pending = &child->pending;

for (i = 0; i < arg.nr; ) {

siginfo_t info;

s32 off = arg.off + i;

spin_lock_irq(&child->sighand->siglock);

list_for_each_entry(q, &pending->list, list) {

if (!off--) {

copy_siginfo(&info, &q->info);

break;

}

spin_unlock_irq(&child->sighand->siglock);

if (off >= 0) /* beyond the end of the list */

break;

#ifdef CONFIG_COMPAT

if (unlikely(is_compat_task())) {

compat_siginfo_t __user *uinfo = compat_ptr(data);

if (copy_siginfo_to_user32(uinfo, &info) ||

__put_user(info.si_code, &uinfo->si_code)) {

ret = -EFAULT;

break;

}

} else

#endif

{

siginfo_t __user *uinfo = (siginfo_t __user *) data;

if (copy_siginfo_to_user(uinfo, &info) ||

__put_user(info.si_code, &uinfo->si_code)) {

ret = -EFAULT;

break;

}

data += sizeof(siginfo_t);

i++;

if (signal_pending(current))

break;

cond_resched();

}

if (i > 0)

return i;

return ret;

}

#ifdef PTRACE_SINGLESTEP

#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)

#else

#define is_singlestep(request) 0

#endif

#ifdef PTRACE_SINGLEBLOCK

#define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)

#else

#define is_singleblock(request) 0

#endif

#ifdef PTRACE_SYSEMU

#define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)

#else

#define is_sysemu_singlestep(request) 0

#endif

static int ptrace_resume(struct task_struct *child, long request,

unsigned long data)

{

if (!valid_signal(data))

return -EIO;

if (request == PTRACE_SYSCALL)

set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

else

clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

#ifdef TIF_SYSCALL_EMU

if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)

set_tsk_thread_flag(child, TIF_SYSCALL_EMU);

else

clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);

#endif

if (is_singleblock(request)) {

if (unlikely(!arch_has_block_step()))

return -EIO;

user_enable_block_step(child);

} else if (is_singlestep(request) || is_sysemu_singlestep(request)) {

if (unlikely(!arch_has_single_step()))

return -EIO;

user_enable_single_step(child);

} else {

user_disable_single_step(child);

}

child->exit_code = data;

wake_up_state(child, __TASK_TRACED);

return 0;

}

#ifdef CONFIG_HAVE_ARCH_TRACEHOOK

static const struct user_regset *

find_regset(const struct user_regset_view *view, unsigned int type)

{

const struct user_regset *regset;

int n;

for (n = 0; n < view->n; ++n) {

regset = view->regsets + n;

if (regset->core_note_type == type)

return regset;

}

return NULL;

}

static int ptrace_regset(struct task_struct *task, int req, unsigned int type,

struct iovec *kiov)

{

const struct user_regset_view *view = task_user_regset_view(task);

const struct user_regset *regset = find_regset(view, type);

int regset_no;

if (!regset || (kiov->iov_len % regset->size) != 0)

return -EINVAL;

regset_no = regset - view->regsets;

kiov->iov_len = min(kiov->iov_len,

(__kernel_size_t) (regset->n * regset->size));

if (req == PTRACE_GETREGSET)

return copy_regset_to_user(task, view, regset_no, 0,

kiov->iov_len, kiov->iov_base);

else

return copy_regset_from_user(task, view, regset_no, 0,

kiov->iov_len, kiov->iov_base);

}

* This is declared in linux/regset.h and defined in machine-dependent

* code. We put the export here, near the primary machine-neutral use,

* to ensure no machine forgets it.

EXPORT_SYMBOL_GPL(task_user_regset_view);

#endif

int ptrace_request(struct task_struct *child, long request,

unsigned long addr, unsigned long data)

{

bool seized = child->ptrace & PT_SEIZED;

int ret = -EIO;

siginfo_t siginfo, *si;

void __user *datavp = (void __user *) data;

unsigned long __user *datalp = datavp;

unsigned long flags;

switch (request) {

case PTRACE_PEEKTEXT:

case PTRACE_PEEKDATA:

return generic_ptrace_peekdata(child, addr, data);

case PTRACE_POKETEXT:

case PTRACE_POKEDATA:

return generic_ptrace_pokedata(child, addr, data);

#ifdef PTRACE_OLDSETOPTIONS

case PTRACE_OLDSETOPTIONS:

#endif

case PTRACE_SETOPTIONS:

ret = ptrace_setoptions(child, data);

break;

case PTRACE_GETEVENTMSG:

ret = put_user(child->ptrace_message, datalp);

break;

case PTRACE_PEEKSIGINFO:

ret = ptrace_peek_siginfo(child, addr, data);

break;

case PTRACE_GETSIGINFO:

ret = ptrace_getsiginfo(child, &siginfo);

if (!ret)

ret = copy_siginfo_to_user(datavp, &siginfo);

break;

case PTRACE_SETSIGINFO:

if (copy_from_user(&siginfo, datavp, sizeof siginfo))

ret = -EFAULT;

else

ret = ptrace_setsiginfo(child, &siginfo);

break;

case PTRACE_GETSIGMASK:

if (addr != sizeof(sigset_t)) {

ret = -EINVAL;

break;

}

if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))

ret = -EFAULT;

else

ret = 0;

break;

case PTRACE_SETSIGMASK: {

sigset_t new_set;

if (addr != sizeof(sigset_t)) {

ret = -EINVAL;

break;

}

if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {

ret = -EFAULT;

break;

}

sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));

* Every thread does recalc_sigpending() after resume, so

* retarget_shared_pending() and recalc_sigpending() are not

* called here.

spin_lock_irq(&child->sighand->siglock);

child->blocked = new_set;

spin_unlock_irq(&child->sighand->siglock);

ret = 0;

break;

}

case PTRACE_INTERRUPT:

* Stop tracee without any side-effect on signal or job

* control. At least one trap is guaranteed to happen

* after this request. If @child is already trapped, the

* current trap is not disturbed and another trap will

* happen after the current trap is ended with PTRACE_CONT.

* The actual trap might not be PTRACE_EVENT_STOP trap but

* the pending condition is cleared regardless.

if (unlikely(!seized || !lock_task_sighand(child, &flags)))

break;

* INTERRUPT doesn't disturb existing trap sans one

* exception. If ptracer issued LISTEN for the current

* STOP, this INTERRUPT should clear LISTEN and re-trap

* tracee into STOP.

if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))

ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);

unlock_task_sighand(child, &flags);

ret = 0;

break;

case PTRACE_LISTEN:

* Listen for events. Tracee must be in STOP. It's not

* resumed per-se but is not considered to be in TRACED by

* wait(2) or ptrace(2). If an async event (e.g. group

* stop state change) happens, tracee will enter STOP trap

* again. Alternatively, ptracer can issue INTERRUPT to

* finish listening and re-trap tracee into STOP.

if (unlikely(!seized || !lock_task_sighand(child, &flags)))

break;

si = child->last_siginfo;

if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {

child->jobctl |= JOBCTL_LISTENING;

* If NOTIFY is set, it means event happened between

* start of this trap and now. Trigger re-trap.

if (child->jobctl & JOBCTL_TRAP_NOTIFY)

ptrace_signal_wake_up(child, true);

ret = 0;

}

unlock_task_sighand(child, &flags);

break;

case PTRACE_DETACH: /* detach a process that was attached. */

ret = ptrace_detach(child, data);

break;

#ifdef CONFIG_BINFMT_ELF_FDPIC

case PTRACE_GETFDPIC: {

struct mm_struct *mm = get_task_mm(child);

unsigned long tmp = 0;

ret = -ESRCH;

if (!mm)

break;

switch (addr) {

case PTRACE_GETFDPIC_EXEC:

tmp = mm->context.exec_fdpic_loadmap;

break;

case PTRACE_GETFDPIC_INTERP:

tmp = mm->context.interp_fdpic_loadmap;

break;

default:

break;

}

mmput(mm);

ret = put_user(tmp, datalp);

break;

}

#endif

#ifdef PTRACE_SINGLESTEP

case PTRACE_SINGLESTEP:

#endif

#ifdef PTRACE_SINGLEBLOCK

case PTRACE_SINGLEBLOCK:

#endif

#ifdef PTRACE_SYSEMU

case PTRACE_SYSEMU:

case PTRACE_SYSEMU_SINGLESTEP:

#endif

case PTRACE_SYSCALL:

case PTRACE_CONT:

return ptrace_resume(child, request, data);

case PTRACE_KILL:

if (child->exit_state) /* already dead */

return 0;

return ptrace_resume(child, request, SIGKILL);

#ifdef CONFIG_HAVE_ARCH_TRACEHOOK

case PTRACE_GETREGSET:

case PTRACE_SETREGSET: {

struct iovec kiov;

struct iovec __user *uiov = datavp;

if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))

return -EFAULT;

if (__get_user(kiov.iov_base, &uiov->iov_base) ||

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