exec/ptrace: fix get_dumpable() incorrect tests

The get_dumpable() return value is not boolean.  Most users of the
function actually want to be testing for non-SUID_DUMP_USER(1) rather than
SUID_DUMP_DISABLE(0).  The SUID_DUMP_ROOT(2) is also considered a
protected state.  Almost all places did this correctly, excepting the two
places fixed in this patch.

Wrong logic:
    if (dumpable == SUID_DUMP_DISABLE) { /* be protective */ }
        or
    if (dumpable == 0) { /* be protective */ }
        or
    if (!dumpable) { /* be protective */ }

Correct logic:
    if (dumpable != SUID_DUMP_USER) { /* be protective */ }
        or
    if (dumpable != 1) { /* be protective */ }

Without this patch, if the system had set the sysctl fs/suid_dumpable=2, a
user was able to ptrace attach to processes that had dropped privileges to
that user.  (This may have been partially mitigated if Yama was enabled.)

The macros have been moved into the file that declares get/set_dumpable(),
which means things like the ia64 code can see them too.

CVE-2013-2929

Reported-by: Vasily Kulikov <segoon@openwall.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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) ||
		    __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
	default:
		break;
	}

	return ret;
}

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) ||
		    __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
	default:
		break;
	}

	return ret;
}
