Security in OpenERP: users, groups Users and user roles are critical points concerning internal security in OpenERP. OpenERP provides several security mechanisms concerning user roles, all implemented in the OpenERP Server. They are implemented in the lowest server level, which is the ORM engine. OpenERP distinguishes three different concepts:
user: a person identified by its login and password. Note that all employees of a company are not necessarily OpenERP users; an user is somebody who accesses the application. group: a group of users that has some access rights. A group gives its access rights to the users that belong to the group. Ex: Sales Manager, Accountant, etc. security rule: a rule that defines the access rights a given group grants to its users. Security rules are attached to a given resource, for example the Invoice model. Security rules are attached to groups. Users are assigned to several groups. This gives users the rights that are attached to their groups. Therefore controlling user roles is done by managing user groups and adding or modifying security rules attached to those groups.
Users
Users represent physical persons using OpenERP. They are identified with a login and a password,they use OpenERP, they can edit their own preferences, ... By default, a user has no access right. The more we assign groups to the user, the more he or she gets rights to perform some actions. A user may belong to several groups.
User groups
The groups determine the access rights to the different resources. A user may belong to several groups. If he belongs to several groups, we always use the group with the highest rights for a selected resource. A group can inherit all the rights from another group
Figure 3 shows how group membership is displayed in the web client. The user belongs to Sales / Manager, Accounting / Manager, Administration / Access Rights, Administration / Configuration and Human Resources / Employee groups. Those groups define the user access rights.
Figure 3: Example of group membership for a given user
Rights
Security rules are attached to groups. You can assign several security rules at the group level, each rule being of one of the following types :
access rights are global rights on an object, record rules are records access filters, fields access right, workflow transition rules are operations rights. You can also define rules that are global, i.e. they are applied to all users, indiscriminately of the groups they belong to. For example, the multi-company rules are global; a user can only see invoices of the companies he or she belongs to.
Concerning configuration, it is difficult to have default generic configurations that suit all applications. Therefore, like SAP, OpenERP is by default pre-configured with best-practices.
Access rights
Access rights are rules that define the access a user can have on a particular object . Those global rights are defined per document type or model. Rights follow the CRUD model: create, read (search), update (write), delete. For example, you can define rules on invoice creation. By default, adding a right to an object gives the right to all records of that specific object.
Figure 4 shows some of the access rights of the Accounting / Accountant group. The user has some read access rights on some objects.
Figure 4: Access rights for some objects.
Record rules
When accessing an object, records are filtered based on record rules. Record rules or access filters are therefore filters that limits records of an object a group can access. A record rule is a condition that each record must satisfy to be created, read, updated (written) or deleted. Records that do not meet the constraints are filtered.
For example, you can create a rule to limit a group in such a way that users of that group will see business opportunities in which he or she is flagged as the salesman. The rule can be salesman = connected_user. With that rule, only records respecting the rule will be displayed.
Field access rights
New in version 7.0.
OpenERP now supports real access control at the field level, not just on the view side. Previously it was already possible to set a groups attribute on a element (or in fact most view elements), but with cosmetics effects only: the element was made invisible on the client side, while still perfectly available for read/write access at the RPC level.
As of OpenERP 7.0 the existing behavior is preserved on the view level, but a new groups attribute is available on all model fields, introducing a model-level access control on each field. The syntax is the same as for the view-level attribute:
_columns = { 'secret_key': fields.char('Secret Key', groups="base.group_erp_manager,base.group_system") } There is a major difference with the view-level groups attribute: restricting the access at the model level really means that the field will be completely unavailable for users who do not belong to the authorized groups:
Restricted fields will be completely removed from all related views, not just hidden. This is important to keep in mind because it means the field value will not be available at all on the client side, and thus unavailable e.g. for on_change calls.
Restricted fields will not be returned as part of a call to fields_get() or fields_view_get() This is in order to avoid them appearing in the list of fields available for advanced search filters, for example. This does not prevent getting the list of a model's fields by querying ir.model.fields directly, which is fine.
Any attempt to read or write directly the value of the restricted fields will result in an AccessError exception.
As a consequence of the previous item, restricted fields will not be available for use within search filters (domains) or anything that would require read or write access.
It is quite possible to set groups attributes for the same field both at the model and view level, even with different values. Both will carry their effect, with the model-level restriction taking precedence and removing the field completely in case of restriction.
Note
The tests related to this feature are in openerp/tests/test_acl.py.
Workflow transition rules
Workflow transition rules are rules that restrict some operations to certain groups. Those rules handle rights to go from one step to another one in the workflow. For example, you can limit the right to validate an invoice, i.e. going from a draft action to a validated action.
Menu accesses
In OpenERP, granting access to menus can be done using user groups. A menu that is not granted to any group is accessible to every user. It is possible in the administration panel to define the groups that can access a given menu.
However, one should note that using groups to hide or give access to menus is more within the filed of ergonomics or usability than within the field of security. It is a best practice putting rules on documents instead of putting groups on menu. For example, hiding invoices can be done by modifying the record rule on the invoice object, and it is more efficient and safer than hiding menus related to invoices.
Views customization
Customizing views based on groups is possible in OpenERP. You can put rules to display some fields based on group rules. However, as with menu accesses customization, this option should not be considered for security concerns. This way of customizing views belongs more to usability.
Administration
When installing your particular instance of OpenERP, a specific first user is installed by default. This first user is the Super User or administrator. The administrator is by default added access rights to every existing groups, as well as to every groups created during a new module installation. He also has access to a specific administration interface accessible via the administration menu, allowing the administration of OpenERP.
The administrator has rights to manage groups; he can add, create, modify or remove groups. He may also modify links between users and groups, such as adding or removing users. He also manages access rights. With those privileges, the administrator can therefore precisely define security accesses of every users of OpenERP.
There are user groups that are between normal groups and the super user. Those groups are Administration / Configuration and Administration / Access Rights. It gives to the users of those groups the necessary rights to configure access rights.
