Commit message: ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME

Fix two issues:

When called for PTRACE_TRACEME, ptrace_link() would obtain an RCU
reference to the parent's objective credentials, then give that pointer
to get_cred().  However, the object lifetime rules for things like
struct cred do not permit unconditionally turning an RCU reference into
a stable reference.

PTRACE_TRACEME records the parent's credentials as if the parent was
acting as the subject, but that's not the case.  If a malicious
unprivileged child uses PTRACE_TRACEME and the parent is privileged, and
at a later point, the parent process becomes attacker-controlled
(because it drops privileges and calls execve()), the attacker ends up
with control over two processes with a privileged ptrace relationship,
which can be abused to ptrace a suid binary and obtain root privileges.

Fix both of these by always recording the credentials of the process
that is requesting the creation of the ptrace relationship:
current_cred() can't change under us, and current is the proper subject
for access control.

This change is theoretically userspace-visible, but I am not aware of
any code that it will actually break.

Fixes: 64b875f7ac8a ("ptrace: Capture the ptracer's creds not PT_PTRACE_CAP")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CVE: CVE-2019-13272
CWE: CWE-264
Vulnerability description: In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to create a ptrace relationship, which allows local users to obtain root access by leveraging certain scenarios with a parent-child process relationship, where a parent drops privileges and calls execve (potentially allowing control by an attacker). One contributing factor is an object lifetime issue (which can also cause a panic). Another contributing factor is incorrect marking of a ptrace relationship as privileged, which is exploitable through (for example) Polkit's pkexec helper with PTRACE_TRACEME. NOTE: SELinux deny_ptrace might be a usable workaround in some environments.

Project: linux
File: ptrace.c

COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
		       compat_long_t, addr, compat_long_t, data)
{
	struct task_struct *child;
	long ret;

	if (request == PTRACE_TRACEME) {
		ret = ptrace_traceme();
		goto out;
	}

	child = find_get_task_by_vpid(pid);
	if (!child) {
		ret = -ESRCH;
		goto out;
	}

	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
		ret = ptrace_attach(child, request, addr, data);
		/*
		 * Some architectures need to do book-keeping after
		 * a ptrace attach.
		 */
		if (!ret)
			arch_ptrace_attach(child);
		goto out_put_task_struct;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL ||
				  request == PTRACE_INTERRUPT);
	if (!ret) {
		ret = compat_arch_ptrace(child, request, addr, data);
		if (ret || request != PTRACE_DETACH)
			ptrace_unfreeze_traced(child);
	}

 out_put_task_struct:
	put_task_struct(child);
 out:
	return ret;
}

Project: linux
File: ptrace.c

SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
		unsigned long, data)
{
	struct task_struct *child;
	long ret;

	if (request == PTRACE_TRACEME) {
		ret = ptrace_traceme();
		if (!ret)
			arch_ptrace_attach(current);
		goto out;
	}

	child = find_get_task_by_vpid(pid);
	if (!child) {
		ret = -ESRCH;
		goto out;
	}

	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
		ret = ptrace_attach(child, request, addr, data);
		/*
		 * Some architectures need to do book-keeping after
		 * a ptrace attach.
		 */
		if (!ret)
			arch_ptrace_attach(child);
		goto out_put_task_struct;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL ||
				  request == PTRACE_INTERRUPT);
	if (ret < 0)
		goto out_put_task_struct;

	ret = arch_ptrace(child, request, addr, data);
	if (ret || request != PTRACE_DETACH)
		ptrace_unfreeze_traced(child);

 out_put_task_struct:
	put_task_struct(child);
 out:
	return ret;
}

Project: linux
File: ptrace.c

void __ptrace_link(struct task_struct *child, struct task_struct *new_parent,
		   const struct cred *ptracer_cred)
{
	BUG_ON(!list_empty(&child->ptrace_entry));
	list_add(&child->ptrace_entry, &new_parent->ptraced);
	child->parent = new_parent;
	child->ptracer_cred = get_cred(ptracer_cred);
}

Project: linux
File: ptrace.c

void __ptrace_unlink(struct task_struct *child)
{
	const struct cred *old_cred;
	BUG_ON(!child->ptrace);

	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

	child->parent = child->real_parent;
	list_del_init(&child->ptrace_entry);
	old_cred = child->ptracer_cred;
	child->ptracer_cred = NULL;
	put_cred(old_cred);

	spin_lock(&child->sighand->siglock);
	child->ptrace = 0;
	/*
	 * 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);
}

Project: linux
File: ptrace.c

int compat_ptrace_request(struct task_struct *child, compat_long_t request,
			  compat_ulong_t addr, compat_ulong_t data)
{
	compat_ulong_t __user *datap = compat_ptr(data);
	compat_ulong_t word;
	kernel_siginfo_t siginfo;
	int ret;

	switch (request) {
	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
		ret = ptrace_access_vm(child, addr, &word, sizeof(word),
				FOLL_FORCE);
		if (ret != sizeof(word))
			ret = -EIO;
		else
			ret = put_user(word, datap);
		break;

	case PTRACE_POKETEXT:
	case PTRACE_POKEDATA:
		ret = ptrace_access_vm(child, addr, &data, sizeof(data),
				FOLL_FORCE | FOLL_WRITE);
		ret = (ret != sizeof(data) ? -EIO : 0);
		break;

	case PTRACE_GETEVENTMSG:
		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
		break;

	case PTRACE_GETSIGINFO:
		ret = ptrace_getsiginfo(child, &siginfo);
		if (!ret)
			ret = copy_siginfo_to_user32(
				(struct compat_siginfo __user *) datap,
				&siginfo);
		break;

	case PTRACE_SETSIGINFO:
		ret = copy_siginfo_from_user32(
			&siginfo, (struct compat_siginfo __user *) datap);
		if (!ret)
			ret = ptrace_setsiginfo(child, &siginfo);
		break;
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
	case PTRACE_GETREGSET:
	case PTRACE_SETREGSET:
	{
		struct iovec kiov;
		struct compat_iovec __user *uiov =
			(struct compat_iovec __user *) datap;
		compat_uptr_t ptr;
		compat_size_t len;

		if (!access_ok(uiov, sizeof(*uiov)))
			return -EFAULT;

		if (__get_user(ptr, &uiov->iov_base) ||
		    __get_user(len, &uiov->iov_len))
			return -EFAULT;

		kiov.iov_base = compat_ptr(ptr);
		kiov.iov_len = len;

		ret = ptrace_regset(child, request, addr, &kiov);
		if (!ret)
			ret = __put_user(kiov.iov_len, &uiov->iov_len);
		break;
	}
#endif

	default:
		ret = ptrace_request(child, request, addr, data);
	}

	return ret;
}

Project: linux
File: ptrace.c

void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
{
	struct task_struct *p, *n;

	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
		if (unlikely(p->ptrace & PT_EXITKILL))
			send_sig_info(SIGKILL, SEND_SIG_PRIV, p);

		if (__ptrace_detach(tracer, p))
			list_add(&p->ptrace_entry, dead);
	}
}

Project: linux
File: ptrace.c

int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
			    unsigned long data)
{
	unsigned long tmp;
	int copied;

	copied = ptrace_access_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE);
	if (copied != sizeof(tmp))
		return -EIO;
	return put_user(tmp, (unsigned long __user *)data);
}

Project: linux
File: ptrace.c

int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
		     void *buf, int len, unsigned int gup_flags)
{
	struct mm_struct *mm;
	int ret;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	if (!tsk->ptrace ||
	    (current != tsk->parent) ||
	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
	     !ptracer_capable(tsk, mm->user_ns))) {
		mmput(mm);
		return 0;
	}

	ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
	mmput(mm);

	return ret;
}

Project: linux
File: ptrace.c

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_REALCREDS);
	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;
	task->ptrace = flags;

	ptrace_link(task, current);

	/* SEIZE doesn't trap tracee on attach */
	if (!seize)
		send_sig_info(SIGSTOP, SEND_SIG_PRIV, 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) {
		/*
		 * We do not bother to change retval or clear JOBCTL_TRAPPING
		 * if wait_on_bit() was interrupted by SIGKILL. The tracer will
		 * not return to user-mode, it will exit and clear this bit in
		 * __ptrace_unlink() if it wasn't already cleared by the tracee;
		 * and until then nobody can ptrace this task.
		 */
		wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE);
		proc_ptrace_connector(task, PTRACE_ATTACH);
	}

	return retval;
}

Project: linux
File: ptrace.c

static int ptrace_detach(struct task_struct *child, unsigned int data)
{
	if (!valid_signal(data))
		return -EIO;

	/* Architecture-specific hardware disable .. */
	ptrace_disable(child);

	write_lock_irq(&tasklist_lock);
	/*
	 * We rely on ptrace_freeze_traced(). It can't be killed and
	 * untraced by another thread, it can't be a zombie.
	 */
	WARN_ON(!child->ptrace || child->exit_state);
	/*
	 * tasklist_lock avoids the race with wait_task_stopped(), see
	 * the comment in ptrace_resume().
	 */
	child->exit_code = data;
	__ptrace_detach(current, child);
	write_unlock_irq(&tasklist_lock);

	proc_ptrace_connector(child, PTRACE_DETACH);

	return 0;
}

Project: linux
File: ptrace.c

static int ptrace_getsiginfo(struct task_struct *child, kernel_siginfo_t *info)
{
	unsigned long flags;
	int error = -ESRCH;

	if (lock_task_sighand(child, &flags)) {
		error = -EINVAL;
		if (likely(child->last_siginfo != NULL)) {
			copy_siginfo(info, child->last_siginfo);
			error = 0;
		}
		unlock_task_sighand(child, &flags);
	}
	return error;
}

Project: linux
File: ptrace.c

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;

	/* Ensure arg.off fits in an unsigned long */
	if (arg.off > ULONG_MAX)
		return 0;

	if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
		pending = &child->signal->shared_pending;
	else
		pending = &child->pending;

	for (i = 0; i < arg.nr; ) {
		kernel_siginfo_t info;
		unsigned long off = arg.off + i;
		bool found = false;

		spin_lock_irq(&child->sighand->siglock);
		list_for_each_entry(q, &pending->list, list) {
			if (!off--) {
				found = true;
				copy_siginfo(&info, &q->info);
				break;
			}
		}
		spin_unlock_irq(&child->sighand->siglock);

		if (!found) /* beyond the end of the list */
			break;

#ifdef CONFIG_COMPAT
		if (unlikely(in_compat_syscall())) {
			compat_siginfo_t __user *uinfo = compat_ptr(data);

			if (copy_siginfo_to_user32(uinfo, &info)) {
				ret = -EFAULT;
				break;
			}

		} else
#endif
		{
			siginfo_t __user *uinfo = (siginfo_t __user *) data;

			if (copy_siginfo_to_user(uinfo, &info)) {
				ret = -EFAULT;
				break;
			}
		}

		data += sizeof(siginfo_t);
		i++;

		if (signal_pending(current))
			break;

		cond_resched();
	}

	if (i > 0)
		return i;

	return ret;
}

Project: linux
File: ptrace.c

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 = ptrace_access_vm(tsk, src, buf, this_len, FOLL_FORCE);

		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;
}

Project: linux
File: ptrace.c

int ptrace_request(struct task_struct *child, long request,
		   unsigned long addr, unsigned long data)
{
	bool seized = child->ptrace & PT_SEIZED;
	int ret = -EIO;
	kernel_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:
		ret = copy_siginfo_from_user(&siginfo, datavp);
		if (!ret)
			ret = ptrace_setsiginfo(child, &siginfo);
		break;

	case PTRACE_GETSIGMASK: {
		sigset_t *mask;

		if (addr != sizeof(sigset_t)) {
			ret = -EINVAL;
			break;
		}

		if (test_tsk_restore_sigmask(child))
			mask = &child->saved_sigmask;
		else
			mask = &child->blocked;

		if (copy_to_user(datavp, mask, 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);

		clear_tsk_restore_sigmask(child);

		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(uiov, sizeof(*uiov)))
			return -EFAULT;

		if (__get_user(kiov.iov_base, &uiov->iov_base) ||
		    __get_user(kiov.iov_len, &uiov->iov_len))
			return -EFAULT;

		ret = ptrace_regset(child, request, addr, &kiov);
		if (!ret)
			ret = __put_user(kiov.iov_len, &uiov->iov_len);
		break;
	}
#endif

	case PTRACE_SECCOMP_GET_FILTER:
		ret = seccomp_get_filter(child, addr, datavp);
		break;

	case PTRACE_SECCOMP_GET_METADATA:
		ret = seccomp_get_metadata(child, addr, datavp);
		break;

	default:
		break;
	}

	return ret;
}

Project: linux
File: ptrace.c

static int ptrace_resume(struct task_struct *child, long request,
			 unsigned long data)
{
	bool need_siglock;

	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);
	}

	/*
	 * Change ->exit_code and ->state under siglock to avoid the race
	 * with wait_task_stopped() in between; a non-zero ->exit_code will
	 * wrongly look like another report from tracee.
	 *
	 * Note that we need siglock even if ->exit_code == data and/or this
	 * status was not reported yet, the new status must not be cleared by
	 * wait_task_stopped() after resume.
	 *
	 * If data == 0 we do not care if wait_task_stopped() reports the old
	 * status and clears the code too; this can't race with the tracee, it
	 * takes siglock after resume.
	 */
	need_siglock = data && !thread_group_empty(current);
	if (need_siglock)
		spin_lock_irq(&child->sighand->siglock);
	child->exit_code = data;
	wake_up_state(child, __TASK_TRACED);
	if (need_siglock)
		spin_unlock_irq(&child->sighand->siglock);

	return 0;
}

Project: linux
File: ptrace.c

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

	if (data & ~(unsigned long)PTRACE_O_MASK)
		return -EINVAL;

	if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
		if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
		    !IS_ENABLED(CONFIG_SECCOMP))
			return -EINVAL;

		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;

		if (seccomp_mode(&current->seccomp) != SECCOMP_MODE_DISABLED ||
		    current->ptrace & PT_SUSPEND_SECCOMP)
			return -EPERM;
	}

	/* 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;
}

Project: linux
File: ptrace.c

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;
}

Project: linux
File: ptrace.c

static void ptrace_unfreeze_traced(struct task_struct *task)
{
	if (task->state != __TASK_TRACED)
		return;

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

	/*
	 * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
	 * Recheck state under the lock to close this race.
	 */
	spin_lock_irq(&task->sighand->siglock);
	if (task->state == __TASK_TRACED) {
		if (__fatal_signal_pending(task))
			wake_up_state(task, __TASK_TRACED);
		else
			task->state = TASK_TRACED;
	}
	spin_unlock_irq(&task->sighand->siglock);
}

Project: linux
File: ptrace.c

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 = ptrace_access_vm(tsk, dst, buf, this_len,
				FOLL_FORCE | FOLL_WRITE);
		if (!retval) {
			if (copied)
				break;
			return -EIO;
		}
		copied += retval;
		src += retval;
		dst += retval;
		len -= retval;
	}
	return copied;
}