Advanced B: ACL and Record Rules

Warning

This tutorial assumes you have completed the Core Training.

To follow the exercise, it is recommended that you fetch the branch 2.0-core from the repository XXX, it contains a version of the module created during the core training we can use as a starting point.

So far we have mostly concerned ourselves with implementing useful features. However in most business scenarios security quickly becomes a concern: currently,

• Any employee (which is what group_user stands for) can create, read, update or delete properties, property types, or property tags.

• If estate_account is installed then only agents allowed to interact with invoicing can confirm sales as that’s necessary to create an invoice.

However:

• We do not want third parties to be able to access properties directly.

• Not all our employees may be real-estate agents (e.g. administrative personnel, property managers, …), we don’t want non-agents to see the available properties.

• Real-estate agents don’t need or get to decide what property types or tags are available.

• Real-estate agents can have exclusive properties, we do not want one agent to be able to manage another’s exclusivities.

• All real-estate agents should be able to confirm the sale of a property they can manage, but we do not want them to be able to validate or mark as paid any invoice in the system.

Note

We may actually be fine with some or most of these for a small business.

Because it’s easier for users to disable unnecessary security rules than it is to create them from nothing, it’s better to err on the side of caution and limiting access: users can relax that access if necessary or convenient.

Groups

See also

The documentation related to this topic can be found in the security reference.

The guidelines document the format and location of master data items.

Goal

At the end of this section,

• We can make employees real-estate agents or real-estate managers.

• The admin user is a real-estate manager.

• We have a new real-estate agent employee with no access to invoicing or administration.

It would not be practical to attach individual security rules to employees any time we need a change so groups link security rules and users. They correspond to roles that can be assigned to employees.

For most Flectra applications 1 a good baseline is to have user and manager (or administrator) roles: the manager can change the configuration of the application and oversee the entirety of its use while the user can well, use the application 2.

This baseline seems sufficient for us:

• Real estate managers can configure the system (manage available types and tags) as well as oversee every property in the pipeline.

• Real estate agents can manage the properties under their care, or properties which are not specifically under the care of any agent.

In keeping with Flectra’s data-driven nature, a group is no more than a record of the res.groups model. They are normally part of a module’s master data, defined in one of the module’s data files.

As simple example can be found here.

what is the category_id?

category_id a module category, it is automatically generated from the category defined in module manifest files.

Exercise

Create the security.xml file in the appropriate folder and add it to the __manifest__.py file.

Add a record creating a group with the id estate_group_user, the name “Agent” and the category base.module_category_real_estate_brokerage.

Below that, add a record creating a group with the id estate_group_manager, the name “Manager” and the category base.module_category_real_estate_brokerage. The estate_group_manager group needs to imply estate_group_user.

Tip

Since we modified data files, remember to restart Flectra and update the module using -u estate.

If you go to Settings ‣ Manage Users and open the admin user (“Mitchell Admin”), you should see a new section:

Set the admin user to be a Real Estate manager.

Exercise

Via the web interface, create a new user with only the “real estate agent” access. The user should not have any Invoicing or Administration access.

Use a private tab or window to log in with the new user (remember to set a password), as the real-estate agent you should only see the real estate application, and possibly the Discuss (chat) application:

Access Rights

See also

The documentation related to this topic can be found at Access Rights.

Goal

At the end of this section,

• Employees who are not at least real-estate agents will not see the real-estate application.

• Real-estate agents will not be able to update the property types or tags.

Access rights were first introduced in Chapter 5: Security - A Brief Introduction.

Access rights are a way to give users access to models via groups: associate an access right to a group, then all users with that group will have the access.

For instance we don’t want real-estate agents to be able to modify what property types are available, so we would not link that access to the “user” group.

Access rights can only give access, they can’t remove it: when access is checked, the system looks to see if any access right associated with the user (via any group) grants that access.

group	create	read	update	delete
A	X	X
B		X
C			X

A user with the groups A and C will be able to do anything but delete the object while one with B and C will be able to read or update, but not search or read.

Note

• The group of an access right can be ommitted, this means the ACL applies to every user, this is a useful but risky fallback as depending on the applications installed it can grant even non-users access to the model.

• If no access right applies to a user, they are not granted access (default-deny).

• If a menu item points to a model to which a user doesn’t have acces and has no submenus which the user can see, the menu will not be displayed.

Exercise

Update the access rights file to:

• Give full access to all objects to your Real Estate Manager group.

• Give agents (real estate users) only read access to types and tags.

• Give nobody the right to delete properties.

• Check that your agent user is not able to alter types or tags, or to delete properties, but that they can otherwise create or update properties.

Warning

Remember to give different xids to your ir.model.access records otherwise they will overwrite one another.

Since the “demo” user was not made a real-estate agent or manager, they should not even be able to see the real-estate application. Use a private tab or window to check for this (the “demo” user has the password “demo”).

Access Rules

See also

The documentation related to this topic can be found at Access Rules.

Goal

At the end of this section, agents will not be able to see the properties exclusive to their colleagues; but managers will still be able to see everything.

Access rights can grant access to an entire model but often we need to be more specific: while an agent can interact with properties in general we may not want them to update or even see properties managed by one of their colleagues.

Access rules provide that precision: they can grant or reject access to individual records:

<record id="rule_id" model="ir.rule">
    <field name="name">A description of the rule's role</field>
    <field name="model_id" ref="model_to_manage"/>
    <field name="perm_read" eval="False"/>
    <field name="groups" eval="[(4, ref('base.group_user'))]"/>
    <field name="domain_force">[
        '|', ('user_id', '=', user.id),
             ('user_id', '=', False)
    ]</field>
</record>

The Search domains is how access is managed: if the record passes then access is granted, otherwise access is rejected.

Tip

Because rules tends to be rather complex and not created in bulk, they’re usually created in XML rather than the CSV used for access rights.

The rule above:

• Only applies to the “create”, “update” (write) and “delete” (unlink) operations: here we want every employee to be able to see other users’ records but only the author / assignee can update a record.

• Is non-global so we can provide an additional rule for e.g. managers.

• Allows the operation if the current user (user.id) is set (e.g. created, or is assigned) on the record, or if the record has no associated user at all.

Note

If no rule is defined or applies to a model and operation, then the operation is allowed (default-allow), this can have odd effects if access rights are not set up correctly (are too permissive).

Exercise

Define a rule which limits agents to only being able to see or modify properties which have no salesperson, or for which they are the salesperson.

You may want to create a second real-estate agent user, or create a few properties for which the salesperson is a manager or some other user.

Verify that your real estate manager(s) can still see all properties. If not, why not? Remember:

The estate_group_manager group needs to imply estate_group_user.

Security Override

Bypassing Security

Goal

At the end of this section, agents should be able to confirm property sales without needing invoicing access.

If you try to mark a property as “sold” as the real estate agent, you should get an access error:

This happens because estate_account tries to create an invoice during the process, but creating an invoice requires the right to all invoice management.

We want agents to be able to confirm a sale without them having full invoicing access, which means we need to bypass the normal security checks of Flectra in order to create an invoice despite the current user not having the right to do so.

There are two main ways to bypass existing security checks in Flectra, either wilfully or as a side-effect:

• The sudo() method will create a new recorset in “sudo mode”, this ignores all access rules and access rights (although hard-coded group and user checks may still apply).

• Performing raw SQL queries will bypass access rules and access rights as a side-effect of bypassing the ORM itself.

Exercise

Update estate_account to bypass access rights and rules when creating the invoice.

Danger

These features should generally be avoided, and only used with extreme care, after having checked that the current user and operation should be able to bypass normal access rights validation.

Operations performed in such modes should also rely on user input as little as possible, and should validate it to the maximum extent they can.

Programmatically checking security

Goal

At the end of this section, the creation of the invoice should be resilient to security issues regardless to changes to estate.

In Flectra, access rights and access rules are only checked when performing data access via the ORM e.g. creating, reading, searching, writing, or unlinking a record via ORM methods. Other methods do not necessarily check against any sort of access rights.

In the previous section, we bypassed the access rules when creating the invoice in action_sold. This bypass can be reached by any user without any access right being checked:

• Add a print to action_sold in estate_account before the creation of the invoice (as creating the invoice accesses the property, therefore triggers an ACL check) e.g.:

  print(" reached ".center(100, '=')
  

• Execute bypass.py in estate_account, giving it the name of your database, and the name of your version of action_sold (unless you named it action_sold then it’s fine)

You should see reached in your Flectra log, followed by an access error.

Danger

Just because you’re already in Python code does not mean any access right or rule has or will be checked.

Currently the accesses are implicitly checked by accessing data on self as well as calling super() (which does the same and updates self), triggering access errors and cancelling the transaction “uncreating” our invoice.

However if this changes in the future, or we add side-effects to the method (e.g. reporting the sale to a government agency), or bugs are introduced in estate, … it would be possible for non-agents to trigger operations they should not have access to.

Therefore when performing non-CRUD operations, or legitimately bypassing the ORM or security, or when triggering other side-effects, it is extremely important to perform explicit security checks.

Explicit security checks can be performed by:

• Checking who the current user is (self.env.user) and match them against specific models or records.

• Checking that the current user has specific groups hard-coded to allow or deny an operation (self.env.user.has_group).

• Calling the check_access_rights(operation) method on a recorset, this verifies whether the current user has access to the model itself.

• Calling check_access_rule(operations) on a non-empty recorset, this verifies that the current user is allowed to perform the operation on every record of the set.

Warning

Checking access rights and checking access rules are separate operations, if you’re checking access rules you usually want to also check access rights beforehand.

Exercise

Before creating the invoice, use check_access_rights and check_access_rule to ensure that the current user can update properties in general, and this specific property in particular.

Re-run the bypass script, check that the error occurs before the print.

Multi-company security

See also

Multi-company Guidelines for an overview of multi-company facilities in general, and multi-company security rules this in particular.

Documentation on rules in general can, again, be found at Access Rules.

Goal

At the end of this section, agents should only have access to properties of their agency (or agencies).

For one reason or an other we might need to manage our real-estate business as multiple companies e.g. we might have largely autonomous agencies, or a franchise setup, or multiple brands (possibly from having acquired other real-estate businesses) which remain legally or financially separate from one another.

Flectra can be used to manage multiple companies inside the same system, however the actual handling is up to individual modules: Flectra itself provides the tools to manage the issue like company-dependent fields and multi-company rules, which is what we’re going to concern outselves with.

We want different agencies to be “siloed” from one another, with properties belonging to a given agency and users (whether agents or managers) only able to see properties linked to their agency.

As before, because this is based on non-trivial records it’s easier for a user to relax rules than to tighten them so it makes sense to default to a relatively stronger security model.

Multi-company rules are simply access rules based on the company_ids or company_id fields:

• company_ids is all the companies to which the current user has access

• company_id is the currently active company (the one the user is currently working in / for).

Multi-company rules will usually use the former i.e. check if the record is associated with one of the companies the user has access to:

<record model="ir.rule" id="hr_appraisal_plan_comp_rule">
    <field name="name">Appraisal Plan multi-company</field>
    <field name="model_id" ref="model_hr_appraisal_plan"/>
    <field name="domain_force">[
        '|', ('company_id', '=', False),
             ('company_id', 'in', company_ids)
    ]</field>
</record>

Danger

Multi-company rules are usually global, otherwise there is a high risk that additional rules would allow bypassing the muti-company rules.

Exercise

• Add a company_id field to estate.property, it should be required (we don’t want agency-less properties), and should default to the current user’s current company.

• Create a new company, with a new estate agent in that company.

• The manager should be a member of both companies.

• The old agent should only be a member of the old company.

• Create a few properties in each company (either use the company selector as the manager or use the agents). Unset the default salesman to avoid triggering that rule.

• All agents can see all companies, which is not desirable, add the record rule restricting this behaviour.

Warning

remember to --update your module when you change its model or data

Visibility != security

Goal

At the end of this section, real-estate agents should not see the Settings menu of the rea-estate application, but should still be able to set the property type or tags.

Specific Flectra models can be associated directly with groups (or companies, or users). It is important to figure out whether this association is a security or a visibility feature before using it:

• Visibility features mean a user can still access the model or record otherwise, either through an other part of the interface or by perform operations remotely using RPC, things might just not be visible in the web interface in some contexts.

• Security features mean a user can not access records, fields or operations.

Here are some examples:

• Groups on model fields (in Python) are a security feature, users outside the group will not be able to retrieve the field, or even know it exists.

  Example: in server actions, only system users can see or update Python code.

• Groups on view elements (in XML) are a visibility feature, users outside the group will not be able to see the element or its content in the form but they will otherwise be able to interact with the object (including that field).

  Example: only managers have an immediate filter to see their teams’ leaves.

• Groups on menus and actions are visibility features, the menu or action will not be shown in the interface but that doesn’t prevent directly interacting with the underlying object.

  Example: only system administrators can see the elearning settings menu.

Exercise

Real Estate agents can not add property types or tags, and can see their options from the Property form view when creating it.

The Settings menu just adds noise to their interface, it should only be visible to managers.

Despite not having access to the Property Types and Property Tags menus anymore, agents can still access the underlying objects since they can still select tags or a type to set on their properties.

1

An Flectra Application is a group of related modules covering a business area or field, usually composed of a base module and a number of expansions on that base to add optional or specific features, or link to other business areas.

2

For applications which would be used by most or every employees, the “application user” role might be done away with and its abilities granted to all employees directly e.g. generally all employees can submit expenses or take time off.