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Most NIS+ operations have implied access control through the permissions on the objects that they manipulate. For example, in order to read an entry in a table, you must have read permission on that entry. However, some NIS+ operations by default perform no access checking at all and are allowed
to all:
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Operation
-
Example of commands that use the operation
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NIS_CHECKPOINT
-
nisping -C
-
NIS_CPTIME
-
nisping, rpc.nisd
-
NIS_MKDIR
-
nismkdir
-
NIS_PING
- nisping, rpc.nisd
-
NIS_RMDIR
-
nisrmdir
-
NIS_SERVSTATE
-
nisbackup, nisrestore
-
NIS_STATUS
-
nisstat, rpc.nispasswdd
The nisopaccess command can be used to enforce access control on these operations on a per NIS+ directory basis.
The directory argument should be the fully qualified name, including the trailing dot, of the NIS+ directory to which nisopaccess will be applied. As a short-hand, if the directory name does not end in a trailing dot, for example "org_dir", then the domain name is appended. The domain name is also appended to partial paths such as "org_dir.xyz".
You can use upper or lower case for the operation argument; however, you cannot mix cases. The "NIS_" prefix may be omitted. For example, NIS_PING can be specified as NIS_PING, nis_ping, PING, or ping.
The rights argument is specified in the format defined by the nischmod(1) command. Since only the read ("r") rights are used to determine who has the right
to perform the operation, the modify and delete rights may be used to control who can change access to the operation.
The access checking performed for each operation is as follows. When an operation requires access be checked on all directories served by its rpc.nisd(1M),
access is denied if even one of the directories prohibits the operation.
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NIS_CHECKPOINT
- Check specified directory, or all directories if there is no directory argument (as is the case when NIS_CHECKPOINT is issued by the "nisping -Ca" command).. Return NIS_PERMISSION when access is denied.
-
NIS_CPTIME
- Check specified directory. It returns 0 when access is denied.
-
NIS_MKDIR
- Check parent of specified directory. Returns NIS_PERMISSION when access is denied.
If the parent directory is not available locally, that is, it is not served by this rpc.nisd(1M), NIS_MKDIR access is allowed, though
the operation will be executed only if this rpc.nisd is a known replica of the directory.
You should note that the NIS_MKDIR operation does not create a NIS+ directory; it adds a directory to the serving list for this rpc.nisd, if appropriate.
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NIS_PING
- Check specified directory. No return value.
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NIS_RMDIR
- Check specified directory. NIS_PERMISSION is returned when access denied.
The NIS_RMDIR operation does not remove a NIS+ directory; it deletes the directory from the serving list for this rpc.nisd, if appropriate.
-
NIS_SERVSTATE
- Check access on all directories served by this rpc.nisd. If access is denied for a tag, "<permission denied>" is returned instead of the tag value.
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NIS_STATUS
- Same as for NIS_SERVSTATE.
Note that older clients may not supply authentication information for some of the operations listed above. These clients are treated as "nobody" when access checking is performed.
The access control is implemented by creating a NIS+ table called "proto_op_access" in each NIS+ directory to which access control should be applied. The table can be manipulated using normal NIS+ commands. However, nisopaccess is the
only supported interface for NIS+ operation access control.
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