1: [[!meta title="A Keylock Security Model for kauth(9)"]]
3: Recently, generic support for electro-mechanical multi-position keylocks
4: in the kernel has been added to NetBSD. Such locks can be turned into
5: various positions, usually up to three or four position. They come with
6: a set of keys that are different in so far as not all positions can be
7: reached with all keys (which key can go up to which position is called
8: the "locking program"). With the new keylock support, such locks can be
9: used to tinker with the kernel security, much like the traditional
10: securelevel variable...
12: The number of keylock positions, the current keylock position, and the
13: overall keylock state can be read within the kernel using a set of
14: functions defined in
16: and userland
17: can access them through the <b>hw.keylock</b> sysctl hierarchy.
19: The following components have been added:
21: * <b>[gpiolock(4)](http://netbsd.gw.com/cgi-bin/man-cgi?gpiolock+4+NetBSD-current)</b>
22: a driver for GPIO attached keylocks.
23: The driver registers with the in-kernel keylock "subsystem". See
26: * <b>secmodel_keylock</b>, a
28: security model that
29: authorizes based on the keylock "closedness". Wheter the rightmost
30: (default) or leftmost position of the keylock means open can be
31: controlled using the <b>hw.keylock.order</b> sysctl variable. This
32: variable can only be changed if the keylock state is OPEN. See
35: The security model is started when a keylock driver registers and
36: stopped when there is no more keylock driver. The keylock security
37: model is optional, keylock support can be used without the security
38: model as well (e.g. to provide keylock state to a userland applications.
39: Useful e.g. for POS applications).
41: The keylock state interpretation is done in
43: and not in the driver itself. This
44: allows for adding support for multiple keylocks in the future. The
45: hw.keylock.pos and hw.keylock.npos sysctl variable have debugging
46: character, the hw.keylock.state variable reflects the state and should
47: be used.
49: Currently, the keylock positions are interpreted as follows: There are
50: maximum four positions, OPEN, SEMIOPEN, SEMICLOSE, CLOSE. What exactly
51: that means leaves room for interpretation right now.... (experience will
52: show what makes sense in the end).
54: To enable the keylock support, the keylock security model, and the
56: driver, add the following lines to your
57: kernel configuration file:
59: options KEYLOCK
60: options secmodel_keylock
61: gpiolock* at gpio?
63: Of course you must have at least one GPIO device in your system for the
65: driver to work and the lock must be
66: connected properly.
68: <b>Please keep in mind that this is an experimental feature...</b>
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