11 KiB
Security
Access control is a vital part of configuring Icinga Web 2 securely. It is important that not every user that has access to Icinga Web 2 can perform any action or see any host and service. Allow only a small group of administrators to change the Icinga Web 2 configuration to prevent mis-configuration and security breaches. Define different rules to users and groups of users which should only see a part of the monitoring environment they're in charge of.
This chapter will describe how to configure such rules in Icinga Web 2 and how permissions, refusals, restrictions and role inheritance work.
Basics
Icinga Web 2 access control is done by defining roles that associate privileges with users and groups. Privileges of a role consist of permissions, refusals and restrictions. A role can inherit privileges from another role.
Role Memberships
A role is tied to users or groups of users. Upon login, a user's roles are identified by the username or names of groups the user is a member of.
Note
Since Icinga Web 2, users in the Icinga configuration and the web authentication are separated, to allow use of external authentication providers. This means that users and groups defined in the Icinga configuration are not available to Icinga Web 2. It uses its own authentication backend to fetch users and groups from, which must be configured separately.
Privileges
Permissions are used to grant access. Whether this means that a user can see a certain area or perform a distinct action is fully up to the permission in question. Without granting a permission, the user will lack access and won't see the area or perform the action.
Refusals are used to deny access. So they're the exact opposite of permissions. Most permissions can be refused. Refusing a permission will block the user's access no matter if another role grants the permission. Refusals override permissions.
Restrictions are expressions that limit access. What this exactly means is up to how the restriction is being utilized. Without any restriction, a user is supposed to see everything. A user that occupies multiple roles, which all define a restriction of the same type, will see more.
Roles
A user can occupy multiple roles. Permissions and restrictions stack up in this case, thus will grant more access. Refusals still override permissions however. A refusal of one role negates the granted permission of any other role.
Configuration
Roles can be changed either through the UI, by navigating to the page Configuration > Authentication > Roles,
or by editing the configuration file /etc/icingaweb2/roles.ini.
Example
The following shows a role definition from the configuration file mentioned above:
[winadmin]
users = "jdoe, janedoe"
groups = "admin"
permissions = "config/*, module/monitoring, monitoring/commands/schedule-check"
refusals = "config/authentication"
monitoring/filter/objects = "host_name=*win*"
This describes a role with the name winadmin. The users jdoe and janedoe are members of it. Just like the
members of group admin are. Full configuration access is granted, except of the authentication configuration,
which is forbidden. It also grants access to the monitoring module which includes the ability to re-schedule
checks, but only on objects related to hosts whose name contain win.
Syntax
Each role is defined as a section, with the name of the role as section name. The following options can be defined for each role in a default Icinga Web 2 installation:
| Name | Description |
|---|---|
| parent | The name of the role from which to inherit privileges. |
| users | Comma-separated list of usernames that should occupy this role. |
| groups | Comma-separated list of group names whose users should occupy this role. |
| permissions | Comma-separated list of permissions granted by this role. |
| refusals | Comma-separated list of permissions refused by this role. |
| unrestricted | If set to 1, owners of this role are not restricted in any way (Default: 0) |
| monitoring/filter/objects | Filter expression that restricts the access to monitoring objects. |
Administrative Roles
Roles that have the wildcard * as permission, have full access and don't need any further permissions. However,
they are still affected by refusals.
Unrestricted roles are supposed to allow users to access data without being limited to a subset of it. Once a user occupies an unrestricted role, restrictions of the same and any other role are ignored.
Inheritance
A role can inherit privileges from another role. Privileges are then combined the same way as if a user occupies all roles in the inheritance path. Or to rephrase that, each role shares its members with all of its parents.
Permissions
Each permission in Icinga Web 2 is denoted by a namespaced key, which is used to group permissions. All permissions
that affect the configuration of Icinga Web 2, are in a namespace called config, while all configuration options
that affect modules are covered by the permission config/modules.
Wildcards can be used to grant all permissions in a certain namespace. The permission config/* grants access to
all configuration options. Just specifying a wildcard * will grant all permissions.
Access to modules is restricted to users who have the related module permission granted. Icinga Web 2 provides
a module permission in the format module/<moduleName> for each installed module.
General Permissions
| Name | Permits |
|---|---|
| * | allow everything, including module-specific permissions |
| application/announcements | allow to manage announcements |
| application/log | allow to view the application log |
| config/* | allow full config access |
| config/access-control/* | allow to fully manage access control |
| config/access-control/groups | allow to manage groups |
| config/access-control/roles | allow to manage roles |
| config/access-control/users | allow to manage user accounts |
| config/general | allow to adjust the general configuration |
| config/modules | allow to enable/disable and configure modules |
| config/navigation | allow to view and adjust shared navigation items |
| config/resources | allow to manage resources |
| user/* | allow all account related functionalities |
| user/application/stacktraces | allow to adjust in the preferences whether to show stacktraces |
| user/password-change | allow password changes in the account preferences |
| user/share/navigation | allow to share navigation items |
module/<moduleName> |
allow access to module <moduleName> (e.g. module/monitoring) |
Monitoring Module Permissions
The built-in monitoring module defines an additional set of permissions, that is described in detail in the monitoring module documentation.
Restrictions
Restrictions can be used to define what a user can see by specifying an expression that applies to a defined set of data. By default, when no restrictions are defined, a user will be able to see the entire data that is available.
The syntax of the expression used to define a particular restriction varies. This can be a comma-separated list of terms, or a full-blown filter. For more details on particular restrictions, check the table below or the module's documentation providing the restriction.
General Restrictions
| Name | Applies to |
|---|---|
| application/share/users | which users a user can share navigation items with (comma-separated list of usernames) |
| application/share/groups | which groups a user can share navigation items with (comma-separated list of group names) |
Username placeholder
It is possible to reference the local username (without the domain part) of the user in restrictions. To accomplish
this, put the macro $user:local_name$ in the restriction where you want it to appear.
This can come in handy if you have e.g. an attribute on hosts or services defining which user is responsible for it:
_host_deputy=$user:local_name$|_service_deputy=$user:local_name$
Filter Expressions
Filters operate on columns. A complete list of all available filter columns on hosts and services can be found in the monitoring module documentation.
Any filter expression that is allowed in the filtered view, is also an allowed filter expression. This means, that it is possible to define negations, wildcards, and even nested filter expressions containing AND and OR-Clauses.
The filter expression will be implicitly added as an AND-Clause to each query on
the filtered data. The following shows the filter expression host_name=*win* being applied on monitoring/filter/objects.
Regular filter query:
AND-- service_problem = 1
|
+--- service_handled = 0
With our restriction applied, any user affected by this restrictions will see the results of this query instead:
AND-- host_name = *win*
|
+--AND-- service_problem = 1
|
+--- service_handled = 0
Stacking Filters
When multiple roles assign restrictions to the same user, either directly or indirectly through a group, all filters will be combined using an OR-Clause, resulting in the final expression:
AND-- OR-- $FILTER1
| |
| +-- $FILTER2
| |
| +-- $FILTER3
|
+--AND-- service_problem = 1
|
+--- service_handled = 0
As a result, a user is be able to see hosts that are matched by ANY of the filter expressions. The following examples will show the usefulness of this behavior:
Example 1: Negation
[winadmin]
groups = "windows-admins"
monitoring/filter/objects = "host_name=*win*"
Will display only hosts and services whose host name contains win.
[webadmin]
groups = "web-admins"
monitoring/filter/objects = "host_name!=*win*"
Will only match hosts and services whose host name does not contain win
Notice that because of the behavior of two stacking filters, a user that is member of windows-admins and web-admins, will now be able to see both, Windows and non-Windows hosts and services.
Example 2: Hostgroups
[unix-server]
groups = "unix-admins"
monitoring/filter/objects = "(hostgroup_name=bsd-servers|hostgroup_name=linux-servers)"
This role allows all members of the group unix-admins to see hosts and services that are part of the host-group linux-servers or the host-group bsd-servers.