Messages in this thread | | | From | "Stephen C. Tweedie" <> | Date | Wed, 2 Feb 2000 13:50:56 +0000 (GMT) | Subject | Re: Capabilities bounding set oddities ? |
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Hi,
On Tue, 1 Feb 2000 00:30:56 +0100 (MET), BIONDI Philippe <Philippe.BIONDI@enst-bretagne.fr> said:
> Why removing CAP_SYS_RAWIO from the cap_bset prevent anyone from mapping a > raw block device but doesn't protect it from reading or writing ?
I assume by "mapping" you mean "binding". The rationale is simple: you may want to grant normal, unprivileged users access to certain raw devices, using normal filesystem permissions to control that access just as you would do for any other device. However, you certainly do _not_ want unprivileged users to be able to unbind or rebind a raw device to which they have access, because that would be equivalent to letting them open any arbitrary block device.
For example, it would be a privileged operation to bind /dev/raw2 to /dev/fd0, but you might then make /dev/raw2 accessible to any user in the group "fd". Opening /dev/raw2 should _not_ allow that user to rebind it to /dev/sda and read the entire raw hard disk!
--Stephen
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