ntpd: Do not allow privsep user to be a privileged user

[Brent Cook]

Since openntpd-portable allows configuring the privsep user, do a
couple of sanity checks at runtime to make sure the privsep user wasn't
configured as root.

This might be overkill.

---
 src/usr.sbin/ntpd/ntp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/usr.sbin/ntpd/ntp.c b/src/usr.sbin/ntpd/ntp.c
index 625364a..c8f095e 100644
--- a/src/usr.sbin/ntpd/ntp.c
+++ b/src/usr.sbin/ntpd/ntp.c
@@ -145,6 +145,12 @@ ntp_main(int pipe_prnt[2], int fd_ctl, struct ntpd_conf 
*nconf,
        conf = nconf;
        setup_listeners(se, conf, &listener_cnt);

+       if (pw->pw_uid == 0 || pw->pw_gid == 0)
+               fatal("privsep user cannot be root");
+
+       if (pw->pw_uid == geteuid() || pw->pw_gid == getegid())
+               fatal("privsep user cannot be the privileged user");
+
        if (setgroups(1, &pw->pw_gid) ||
            setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
            setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
--
1.9.1