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Date: Tue, 16 May 1995 07:45:21 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199505152145.HAA10950@godzilla.zeta.org.au>
To: bde@zeta.org.au, current@FreeBSD.org, mark@linus.demon.co.uk
Subject: Re: MAKEDEV and device permissions
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>I would agree with the performance argument if it were significant or
>if there were no other factor involved.  However, in my opinion it's
>more important to make scripts like MAKEDEV as obvious as possible to
>reduce the chance that security holes creep in.  I find it easier to
>read device modes directly than having to work out octal complements
>on the fly.

You still have to be aware of the umasks unless everything is chmod'ed.
I think chmod'ing everything would be too verbose.

>Rod showed me a candidate patch which seemed to confuse umasks with
>modes (in favour of modes :-), which resulted in some calls to "umask
>37" and some to "umask 026" to do the same thing...

I started removing the execute bits from the umasks since they are
irrelevant for devices (mknod masks them anyway) and wrong for directories.

>> Tapes were always supposed to be operator-writeable.  This will be fixed
>> in 2.0.5.  I have the raw floppy operator-writeable locally too, but I
>> don't think it is right for general use because floppies can be mounted.

>I miss the point here.  Only root can mount/umount.  Is there a problem
>with the operator writing to a device containing a mounted file system?
>I thought that type of thing was already prohibited by the kernel.

Yes, you write to the device while it is not mounted and wait for root
to mount it.

Bruce