Security Mechanisms
Current situation
Current logical controls:
- ANONYMOUS_ACCESS = ‘deny’
- Deny or allow anonymous access to the web interface
- ANONYMOUS_REGISTER = ‘deny’
- Deny or allow anonymous users to register through the web interface
- ANONYMOUS_REGISTER_MAIL = ‘deny’
- Deny or allow anonymous users to register through the mail interface
Current user interface authentication and controls:
- command-line tool access controlled with passwords, but no logical controls
- CGI access is by username and password and has some logical controls
- mailgw access is through identification using sender email address, with limited functionality available
The web interface implements has specific logical controls, preventing non-admin users from accessing:
- other user’s details pages
- listing the base classes (not issues or their user page)
- editing base classes
Issues
- The current implementation is ad-hoc, and not complete for all use cases.
- Currently it is not possible to allow submission of issues through email but restrict those users from accessing the web interface.
- Only one user may perform admin functions.
- There is no verification of users in the mail gateway by any means other than the From address. Support for strong identification through digital signatures should be added.
- The command-line tool has no logical controls.
- The anonymous control needs revising - there should only be one way to be an anonymous user, not two (currently there is user==None and user==’anonymous’).
Possible approaches
Security controls in Roundup could be approached in three ways:
- at the hyperdb level, with read/write/modify permissions on classes, items and item properties for all or specific transitions.
- at the user interface level, with access permissions on CGI interface methods, mailgw methods, roundup-admin methods, and so on.
- at a logical permission level, checked as needed.
In all cases, the security built into roundup assumes restricted access to the hyperdatabase itself, through operating-system controls such as user or group permissions.
Hyperdb-level control
Control is implemented at the Class.get, Class.set and Class.create level. All other methods must access items through these methods. Since all accesses go through the database, we can implement deny by default.
Pros:
- easier to implement as it only affects one module
- smaller number of permissions to worry about
Cons:
- harder to determine the relationship between user interaction and hyperdb permission.
- a lot of work to define
- must special-case to handle by-item permissions (editing user details, having private messages)
User-interface control
The user interfaces would have an extra layer between that which parses the request to determine action and the action method. This layer controls access. Since it is possible to require methods be registered with the security mechanisms to be accessed by the user, deny by default is possible.
Pros:
- much more obvious at the user level what the controls are
Cons:
- much more work to implement
- most user interfaces have multiple uses which can’t be covered by a single permission
Logical control
At each point that requires an action to be performed, the security mechanisms are asked if the current user has permission. Since code must call the check function to raise a denial, there is no possibility to have automatic default of deny in this situation.
Pros:
- quite obvious what is going on
- is very similar to the current system
Cons:
- large number of possible permissions that may be defined, possibly mirroring actual user interface controls.
- access to the hyperdb must be strictly controlled through program code that implements the logical controls.
Action
The CGI interface must be changed to:
- authenticate over a secure connection
- use unique tokens as a result of authentication, rather than pass the user’s real credentials (username/password) around for each request (this means sessions and hence a session database)
- use the new logical control mechanisms
- implement the permission module
- implement a Role editing interface for users
- implement htmltemplate tests on permissions
- switch all code over from using config vars for permission checks to using permissions
- change all explicit admin user checks for Role checks
- include config vars for initial Roles for anonymous web, new web and new email users
The mail gateway must be changed to:
- use digital signatures
- use the new logical control mechanisms
- switch all code over from using config vars for permission checks to using permissions
The command-line tool must be changed to:
- use the new logical control mechanisms (only allowing write access by admin users, and read-only by everyone else)