Annotation of wikisrc/users/mbalmer/keylock.mdwn, revision 1.2

1.2     ! mbalmer     1: [[!meta title="A Keylock Security Model for kauth(9)"]]
1.1       mbalmer     2: 
                      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...
                     11: 
                     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
1.2     ! mbalmer    14: functions defined in
        !            15: [keylock.h](http://cvsweb.de.netbsd.org/cgi-bin/cvsweb.cgi/src/sys/dev/keylock.h?rev=HEAD)
        !            16: and userland
        !            17: can access them through the <b>hw.keylock<b> sysctl hierarchy.
1.1       mbalmer    18: 
                     19: The following components have been added:
                     20: 
                     21: * '''{{manual page|gpiolock|4|}}''' a driver for GPIO attached keylocks.
                     22:  The driver registers with the in-kernel keylock "subsystem". See
                     23: {{src|gpiolock.c|sys/dev/gpio/gpiolock.c}}.
                     24: 
                     25: * '''secmodel_keylock''', a {{manual page|kauth|9}} security model that
                     26: authorizes based on the keylock "closedness".  Wheter the rightmost
                     27: (default) or leftmost position of the keylock means open can be
                     28: controlled using the '''hw.keylock.order''' sysctl variable. This
                     29: variable can only be changed if the keylock state is OPEN. See
                     30: {{src|secmodel_keylock.c|sys/secmodel/keylock/secmodel_keylock.c}}.
                     31: 
                     32: The security model is started when a keylock driver registers and
                     33: stopped when there is no more keylock driver.  The keylock security
                     34: model is optional, keylock support can be used without the security
                     35: model as well (e.g. to provide keylock state to a userland applications.
                     36: Useful e.g. for POS applications).
                     37: 
                     38: The keylock state interpretation is done in
                     39: {{src|keylock.c|sys/dev/keylock.c}} and not in the driver itself.  This
                     40: allows for adding support for multiple keylocks in the future.  The
                     41: hw.keylock.pos and hw.keylock.npos sysctl variable have debugging
                     42: character, the hw.keylock.state variable reflects the state and should
                     43: be used.
                     44: 
                     45: Currently, the keylock positions are interpreted as follows:  There are
                     46: maximum four positions, OPEN, SEMIOPEN, SEMICLOSE, CLOSE.  What exactly
                     47: that means leaves room for interpretation right now.... (experience will
                     48: show what makes sense in the end).
                     49: 
                     50: To enable the keylock support, the keylock security model, and the
                     51: {{manual page|gpiolock|4|}} driver, add the following lines to your
                     52: kernel configuration file:
                     53: 
                     54:        options KEYLOCK
                     55:        options secmodel_keylock
                     56:        gpiolock* at gpio?
                     57: 
                     58: Of course you must have at least one GPIO device in your system for the
                     59: {{manual page|gpiolock|4|}} driver to work and the lock must be
                     60: connected properly.
                     61: 
                     62: Please keep in mind that this is an experimental feature...

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