Re: permissions of tty devices
In article <[🔎] 20010731142735.4905.qmail@cthulhu.rlyeh.org>,
Pawel Wiecek <coven@vmh.net> wrote:
>On Jul 31, 4:15pm, Russell Coker wrote:
>> > I guess utils like write will not work without it...
>> That depends on mesg. If mesg would make the device world writable inste=
>> ad=20
>> of tty group writable then write etc would work fine without it.
>
>Yes, but:
> 1. it doesn't
> 2. would you REALLY like anyone to be able to write tou your terminal with
> cat? I wouldn't.
If you have a group 'tty' in /etc/group, but you're not using it
on the tty devices in /dev, then 'mesg' gets confused. It assumes
that when it finds a group 'tty', you're going to use it.
With a group tty: - only check and modify the 'group' write bit
Without group tty: - check and modify 'group + other' bit
The changes in 2.80 were inspired by several reports I got from people
who had done a security audit on sysvinit - I think it makes sense.
As Pawel says, do you really want your tty device world-writeable?
I think that the changes to 'mesg' have served their purpose
nicely - you're now aware of the problem.
Mike.
--
"dselect has a user interface which scares small children"
-- Theodore Tso, on debian-devel
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