Alan Cox wrote:
On Wed, Feb 13, 2008 at 05:52:21PM -0600, Les Mikesell wrote:
But why not just block any other access? A tape drive wouldn't work
Because the device changes ownership
Traditional unix behavior is that open file descriptors stay open and
working even if access permissions change.
well with 2 writers but unix systems can usually prevent that without
breaking a running session because someone else logs in nearby.
Different thing altogether.
If a previos session could snoop your keystrokes, watch your desktop and
borrow your bank card details you would be suprised and I suspect cross. Audio
and video snooping via sound card/web camera is no different.
If something needs exclusive access, it should arrange for exclusive
access and just not work until it can get it (i.e. politely wait its
turn instead of rudely breaking a working process). I can see where
this might make sense on the VT keyboard since that device is
necessarily shared during the procedure. But it doesn't make any more
sense to interrupt a running phone or music player session because
someone else is temporarily using a certain keybord than it would to
break a running tape backup for the same circumstance. Or at least this
should be left as an easily chosen local policy.
With controls based on ownership, can't root still do the snooping
operations you are concerned about anyway? Fedora is probably mostly
used on machines with only a few users, so chances are that the owner of
the first session being interrupted has root access anyway and could
bypass the access restrictions the switch tries to impose. Wouldn't it
be better to kernel locking or some mechanism that can really ensure
exclusive access for situations like a phone session?
--
Les Mikesell
lesmikesell@xxxxxxxxx
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