last changed: 12-May-98

First simple trustee handling is added in 0.99.pl9.

some notes/restrictions:

NOT ALL functions will work correct with trustees rights.
Trustee handling still needs to be hard tested to avoid 
SECURITY holes.

- trustee handling must be activated by setting the volumes 't' flag.
- if activated for the SYS directory then the following default 
  trustees should be set.
  GROUP EVERYBODY: C         in SYS:MAIL
                   FR        in SYS:PUBLIC
  SUPERVISOR:      SRWCEMFA  in SYS:

  the standard user rights in mail diretories are not so important, 
  because user has unix rights in this diretory.
  every USER:      RWCEMF in SYS:MAIL/userid

  A non root supervisor and user with supervisor equivalences 
  get default full trustee rights in root directory. These rights
  could be altered in subdirectories to less rights.
  A root supervisor always has full rights.

- if SYS volume is marked as trusttee volume then some
  checking routines will reduce g+o unix accesses in
  SYS:MAIL subdirectories.
- symlink directories must get direct trustees, inheritated_mask
  is set to 0 to prevent user making symlinks to directories
  they do not have real access.
- when stepping through directories, 
  inheritated_mask will be set to 0 if st_dev changes.
- only root assigned user may give trustee rights to 
  file/dir which st_dev differs from VOLUMES st_dev.
- only additional rights are given by trustees, existing
  unix user rights are not reduced.
  therefore trustee volumes should get low unix rights.
  for example:  0711 for directories and 0600 for files.
- for many routines the user still needs the 'x' directory right.
- the trusttee search is limitated to user and first level groups.
  'group in group' and 'normal' security equivalences are not supported.
  Supervisor equivalences are supported.
- an user can only be member of 32 groups.
- some changes of trustees only have effect after new login.
- must never be switched on volumes which do not have fix inodes,
  because trustees are represented by device and inode number of the
  file or directory.

- standard trustee directory is /var/nwserv/trustees 
  ( see nwserv.conf section 47 )

- representation under this directory is:
  - for user trustees:
    volumename/device/ino0/ino1/ino2/t.ino3/id -> trustee
    ino0 .. ino3 = byte 0 .. 3 of inode
    id = user id as hex number.
  - for inherit right masks  ( we use 'userid' 0 )
    volumename/device/ino0/ino1/ino2/t.ino3/0  -> inherit_right_mask
  - and for scanning trustees:
    volumename/device/ino0/ino1/ino2/n.ino3 -> path
    path is relativ to volumes root path.
  - and for 'trustees are changed' notifications:
    volumename/ts -> sernum (hex value)
  all values are represented by symbolic links, not files similar
  to the attribute handling.


  

 
