another ttyS0 acces problem ;-)

[Dave Platt]

In article <20011015.152152.134646080.0.lawson_whitney at juno.com>,
 <wine-users at winehq.com> wrote:

>> I did chmod 666 /dev/ttyS0, made it group "users" r/w/x for all, suid and
>> gid but still no suxes.
>
>What in the name of Babbage do you think suid and gid are spoze to do to
>a comm port?

Control who's allowed to open the serial port!

On most Unix-type systems, the serial ports are under relatively
strict control by default.  This is done in order to keep an
unprivileged user application from, for example, opening a /dev/ttyNN
which is connected to a dialup modem, and then pretending to be the
login process and spoof people into entering their passwords.

On most Linux distributions I've used, the tty devices are given the
gid of a specialized group, and are made group read/write (e.g.
permissions 0660) .  Users who are trusted enough to be allowed to
access the ports are given membership into the tty group.  Untrusted
users are not, and can't open tty devices.

-- 
Dave Platt                                           dplatt at radagast.org
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