Editor With NO Shell Access?

[Edward M.]

On 03/12/2012 05:33 PM, Robert Bonomi wrote:
>>  From owner-freebsd-questions at freebsd.org  Mon Mar 12 17:46:04 2012
>> Date: Mon, 12 Mar 2012 15:47:59 -0700
>> From: "Edward M."<eam1edward at gmail.com>
>> To: Polytropon<freebsd at edvax.de>
>> Cc: freebsd-questions at freebsd.org
>> Subject: Re: Editor With NO Shell Access?
>>
>> On 03/12/2012 03:23 PM, Polytropon wrote:
>>> On Mon, 12 Mar 2012 15:19:51 -0700, Edward M. wrote:
>>>> On 03/12/2012 03:10 PM, Polytropon wrote:
>>>>> /etc/shells to work, but a passwd entry like
>>>>>
>>>>>      bob:*:1234:1234:Two-loop-Bob:/home/bob:/usr/local/bin/joe
>>>>      I think this would not  let the user to login,etc
>>> I'm not sure... I assume logging in is handled by /usr/bin/login,
>>> and control is then (i. e. after successful login) transferred
>>> to the login shell, which is the program specified in the
>>> "shell" field (see "man 5 passwd") of /etc/passwd. How is
>>> login supposed to know if the program specified in this
>>> field is actually a dialog shell?
>>>
>>>   From "man 1 login" I read that many shells have a built-in
>>> login command, but /usr/bin/login is the system's default
>>> binary for this purpose if the "shell" (quotes deserved if
>>> it is an editor as shown in my assumption) has no capability
>>> of performing a login.
>>>
>>>
>>>
>>      Now i gotta try this out.   Off to
>>      hosed my system.
> If other configuration is set up right (e.g. /etc/shells), you can name
> *any* executable as the 'shell' field in /etc/passwd, and have it work.
>
> "Long, long, ago", I used this for client 'on demand' system back-up.  They
> just put the tape in the drive, and logged in as the 'backup' user.
>
>
> *HOWEVER* this is -not- a solution for the OP's "problem", as a skilled,
> _malicious_, user can change, say,  vi(1)'s idea of what executable it
> should invoke when a '!', or '!!' command is issued.
      I tried it out of curiosity to see if it was possible to  login 
in  joe, by the way the OS was configure.
      However my knowledge is not advance to continue, got stock on the 
message
      cannot  not find "*-joerc" :-)

      Regards
      Ed