No, there is not a password-entry field. This is not the lock screen by traditional desktop metaphors, this is the "curtain". It comes on when the screen blanks, except unlike an actual screensaver, it's designed to show the system clock and notifications.
Besides, typing the full password is worse than swiping, unless the user has a worryingly short password.
@email@example.com perhaps my Ubuntu is a poor example, recently upgraded from 14.04 or so. I get a regular password entry field.
On my fedora laptop, when the screen blanks, I get a screen with the time, I can swipe up, but I can also just start typing the password, and it accepts it, and unlocks.
Maybe I'm just getting a different experience.
This is the default 17.10 session; the GNOME Shell I mentioned in the original post is the culprit. The problem is that there is NO "blank the screen on inactivity" setting. If I want to lock the session and get the lock screen, there is an option for that. What I do not want to do is have to type my password every time the screen-saver-blanking happens, which is a dozen or more times a day.