Bizzare paranoia of /bin/login on 3b2

[Steven Bellovin]

> I have experienced a bizzare problem with logging in on the console
> on our 3b2.  Here's what would happen:  Unix: would send  login: , I
> would reply, then Unix would send Login incorrect immediately without
> asking for a password.  I immediately feared that something happened
> to /etc/passwd.  But I went to other terminals and was able to login
> without any problem.  Then I found that the console would allow me to
> login as guest, which didn't have a password, but from guest, su
> replied with Sorry without asking for a password.  When on as guest,
> the ps command reported that my login -sh was not associated with
> a terminal.
> 	The only major change I had recently made of significance was
> to change a line in /etc/inittab from a uugetty to a shell script
> that did a few things, then exec'd uugetty.  Doing a ps from another
> terminal revealed that this shell script was associated with console.
> 	So apparently, for some reason INIT made the shell script in
> console group, and when login started up on the console it didn't like
> having another process associated with console and got suspicious.
> Switching back the /etc/inittab line solved the problem.

It's not a matter of suspicion or paranoia; rather, because something else
had the console open first the getty for it didn't get the proper process
group, and hence getpass() couldn't open /dev/tty.  I've seen this once or
twice myself; rebooting made the problem go away.