Description

rbac

, RBAC

- role-based access control

Role-based access control allows system administrators to delegate the administrative control of parts of the system to users. Users can be given the ability to run commands with additional privileges in two ways:

by assigning a profile directly to the user, in which case no additional authentication is required
by creating a role and assigning the profiles to the role. It can also be used to build restrictive environments for users by removing their ability to run commands they would normally be allowed to run.

Profiles

Profiles are named collections of commands and authorizations that are run with additional privilege and/or a specific real and effective UID and GID. For example, most of the printer system can be managed by having the lp commands run with the UID or lp. Some commands need privileges as defined in privileges(5) to run. For example, the “Process Management” profile allows a user to run the kill command with the proc_owner privilege so that it can send signals to processes it does not own.

See exec_attr(4) and prof_attr(4) for information about how the administrator can extend the system-provided profiles and create their own. Profile configuration can be stored in any of the currently supported name services (files, NIS, LDAP).

Profiles can also be used with the Service Management Facility (SMF) to control the privileges and UID/GID with which a service runs. See smf_security(5) for more information.

Roles

A role is a special shared account that cannot directly login to the system that can only be accessed by authorized users with the su(1M) command or over the network with ssh(1) when using host-based authentication or GSS-API authentication. It can not login with rlogin(1), telnet(1), or gdm.

A role has a UID, a password, and a home directory just like a normal user. Authentication to the role can be either with the user's own password or with the per-role password (the roleauth keyword in user_attr(4) controls that behavior on a per-role basis). Usually a role's login shell is one of the profile shells (pfsh(1), pfksh(1), pfcsh(1)) that are granted one or more Profiles, allowing the role to always execute commands with privilege.

A role is normally needed only if a shared account environment is required. Usually assigning profiles directly to the user is sufficient.

The root user can be configured to be a role using the usermod(1M) command. This ensures that only authorized users can become root even when the root password is more widely known.

# usermod -K type=role root

Making root a role does not restrict access to single user mode. The system console should be protected using other means, such as setting a security password with eeprom(1M).

Authorizations

An authorization is a unique string that represents a user's right to perform some operation or class of operations. Authorizations are normally only checked by programs that always run with some privilege, for example the setuid(2) programs such as cdrw(1) or the system cron(1M) daemon.

Authorization definitions are stored in the auth_attr(4) database. For programming authorization checks, only the authorization name is significant.

Some typical values in an auth_attr database are as follows:

solaris.jobs.:::Cron and At Jobs::help=JobHeader.html
solaris.jobs.grant:::Delegate Cron & At \
    Administration::help=JobsGrant.html
solaris.jobs.admin:::Manage All Jobs::help=AuthJobsAdmin.html
solaris.jobs.user:::Cron & At User::help=JobsUser.html

Authorization name strings ending with the grant suffix are special authorizations that give a user the ability to delegate authorizations with the same prefix and functional area to other users.

All authorization names starting with solaris are reserved for allocation by the operating system vendor. Developers and administrators may create their own top level namespace; use of a unique identifier such as the company name, DNS domain name, or application name is suggested.

Authorization Checks

To check authorizations from C code, developers should use the chkauthattr(3C) library function, which verifies whether or not a user has a given authorization.

Authorizations can be explicitly checked in shell scripts by checking the output of the auths(1) utility. For example,

for auth in `auths      | tr , " "` NOTFOUND
do
    ["$auth" = "solaris.date" ] && break      # authorization found
done

if [ "$auth" != "solaris.date" ]
then
    echo >&2 "$PROG: ERROR: you are not authorized to set the date"
    exit 1
fi

Authorizations are also used by the Service Management Facility (SMF) to control which users can change the state of a service or reconfigure a service. See smf_security(5) for more information.

Comparison with sudo(1M)

RBAC in Solaris provides a similar set of functionality to sudo(1M) that is often provided with UNIX or UNIX-like systems. It is provided on the Companion CD for Solaris.

One of the most obvious differences between Solaris RBAC and sudo is the authentication model. In sudo, users reauthenticate as themselves. In Solaris RBAC, either no additional authentication is needed (when profiles are assigned directly to the user) or the user authenticates to a shared account called a role.

Using the NOPASSWD functionality in sudo is similar to assigning the profile to the user and having the user execute the command using pfexec(1). For example, if sudoers(4) allows the user to run kill(1) as UID 0 but without authentication (NOPASSWD), the user would run:

$ sudo kill -HUP 1235

In Solaris RBAC, if the user has a normal (that is, no profile) login shell, the user would execute the equivalent operation by being assigned the “Process Management” profile and would use pfexec as follows:

$ pfexec kill -HUP 1235

If the user has a profile shell (such as pfsh) as the login shell, then kill will always run with the additional privilege without the need of a “prefix”. For example,

$ kill -HUP 1235

An RBAC role is similar in concept to the User_Alias in sudoers(4), except that the role password rather than the user password is required.

Execution profiles exec_attr(4) entries) in RBAC are similar to the Cmnd_Alias in sudoers.

There is currently no equivalent of the Host_Alias sudo(1M) functionality in Solaris RBAC.

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	man pages section 5: Standards, Environments, and Macros Oracle Solaris 11.1 Information Library