===================
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
======

1. The current implementation is ad-hoc, and not complete for all use cases.
2. Currently it is not possible to allow submission of issues through email
   but restrict those users from accessing the web interface.
3. Only one user may perform admin functions.
4. 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.
5. The command-line tool has no logical controls.
6. 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:

1) at the hyperdb level, with read/write/modify permissions on classes, items
   and item properties for all or specific transitions.
2) at the user interface level, with access permissions on CGI interface
   methods, mailgw methods, roundup-admin methods, and so on.
3) 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)