Security Plugins Documentation
Introduction
This document describes the structure and design of Qpid security plugins, for
the Java broker. In particular, the new Access Control plugin, which implements
the same ACL file syntax as the C++ broker, is examined in detail. The security
plugins use the broker's OSGi bundle functionality to manage their lifecycle,
and the ConfigurationPlugin
mechanism to manage their configuration via the
Apache commons configuration XML configuration file.
The Java interfaces and packages used by the security plugins are described here,
although the Javadoc documentation generated from the source should also be
consulted, and as always reading the source should provide further insight and information.
Use Cases
The following use cases were identified and used to drive the design and development
of both the security plugin mechanism in general, and the access control plugin in particular.
Allow access to broker functions to be controlled by an ACL, with the checks being
carried out independently of the mechanism used to access the broker. This would
mean that a single CREATE permission would apply whether the queue was
created when a user logged in and used it, or if that user connected to the broker
via JMX or QMF and used the management operations to create the queue.
Permissions must be definable at a virtualhost level, with fallback to global
permissions. This allows access to be granted for operations only on a certain
host, while global operations such as broker administration can be defined at
the global level. It also allows default behaviour to be specified globally and
then overridden on a per-host basis.
The ACL mechanism controls access to operations on particular objects for all users,
if at least one user has a rule controlling access to that operation on that type of
object. This means that all users requiring access to a particular operation must be
configured. The default behaviour will be to deny access.
It should be possible for the addition of one access control rule to trigger the
addition of other rules, to simplify creation of rulesets.
The behaviour of the access control mechanism should be configurable.
The Java and C++ brokers should share a common configuration file format.
It should be possible to configure access to not just internal broker application
objects, but to the management operations and attributes of the broker, as well
as to external objects such as plugins.
As long as a suitably authenticated channel is used to connect, access control
rules should be applied when performing operations on broker objects. This does
not hold when, for example, an operator has local access and is using JConsole
to manage the broker.
Java Interfaces, Packages and Classes
This section describes the Java artifacts that are involved in security plugin development.
They are mostly contained in the package org.apache.qpid.server.security
which
is part of the broker code. It is recommended that a package prefix is chosen for new
security plugins, and this should be used to form the packages for the implementing classes.
In general, when creating a new plugin, you need three classes. These would be the main
PluginName
class, which should implement the SecurityPlugin
interface and have a public static instance of an anonymous internal classes that implements
SecurityPluginfactory
. Additionally, the PluginNameConfiguration
class, which should implement the ConfigurationPlugin
interface and have a
public static instance of an anonymous internal classes that implements
ConfigurationPluginfactory
, and finally the PluginNameActivator
class, which should extend the SecurityPluginActivator
abstract class
and implement the required methods exposing the factories from the other classes.
These classes need to be visible from the broker, so they should be placed in the
org.apache.qpid.server.security.pluginname.plugins
package, which should be
listed in the manifest file. Any internal classes for the plugin should be placed in
the org.apache.qpid.server.security.pluginname.config
package which
should be marked as provate in the manifest.
If logging using the actor and subject framework is required, the property file should
be located in the org.apache.qpid.server.security.pluginname.logging
package, and this should also be exported in the manifest file.
OSGi
The security plugins are now loaded using the Felix OSGi container, which is started
as an embedded process inside the broker. This loads all plugin .jar files from the
directory named in the plugin-directory
configuration element, cacheing them in the
cache-directory
directory. Note that, at present, the cache directory is cleared at
startup, although this behaviour may change. To create OSGi plugin bundles, a manifest
file - MANIFEST.MF
is created that specifies certain attributes of the bundle. A
sample manifest file for one of the security plugins is shown below.
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Qpid Broker-Plugins PluginName
Bundle-SymbolicName: broker-plugins-pluginname
Bundle-Description: Name description.
Bundle-License: http://www.apache.org/licenses/LICENSE-2.0.txt
Bundle-DocURL: http://www.apache.org/qpid/pluginname.html
Bundle-Version: 1.0.0
Bundle-Activator: org.apache.qpid.server.security.pluginname.plugins.PluginNameActivator
Bundle-RequiredExecutionEnvironment: JavaSE-1.5
Bundle-ActivationPolicy: lazy
Import-Package: org.apache.qpid
Private-Package: org.apache.qpid.server.security.pluginname.config,
org.apache.qpid.server.security.pluginname.logging
Export-Package: org.apache.qpid.server.security.pluginname.plugins
The complete list of packages to import will be determined by the actual operation of
the plugin, however the number of exported packages should be kept to a minimum.
Plugin
This is the main interface to be extended by all plugins. It contains a
method that allows configuration via the ConfigurationPlugin
mechanism.
public void configure(ConfigurationPlugin config);
PluginFactory and SecurityPluginFactory
These factories are used to initialise instances of plugins and configure them appropriately.
The factories are managed by the OSGI framework started by the PluginManager
,
which is also used to retrieve the instances.
public Class<P> getPluginClass();
public String getPluginName();
public P newInstance(ConfigurationPlugin config) throws ConfigurationException;
SecurityPlugin
This is the interface that defines security plugins. The getDefault
method
returns the default result for the plugin when no configuration is found for some
situation.
The authorise
method is the main entry-point to the plugin, and is called
by the SecurityManager
with the relevant paramaters. Similarly, the
access
method is used for the special case of controlling access to
the entire virtual host, and the
Result getDefault();
Result access(ObjectType objectType, Object instance);
Result authorise(Operation operation, ObjectType objectType, ObjectProperties properties);
SecurityPluginActivator
The activator registers the factories with the OSGI framework, based on the
implementations of the abstract methods.
public abstract SecurityPluginFactory getFactory();
public abstract ConfigurationPluginFactory getConfigurationFactory();
AbstractPlugin
This is a simple parent class, which allows a common point of extension
for shared plugin code. Currently it simply implements the interface with
abstract methods.
public abstract Result access(ObjectType object, Object instance);
public abstract Result authorise(Operation operation, ObjectType object, ObjectProperties properties);
AbstractProxyPlugin
This class is designed to be extended by plugins that only wish to take part in a subset
of the possible security descisions. Normally, a call to the authorise
method
is proxied to one of the provided methods, based on the operation, for example a CONSUME
access control check would be proxied to the authoriseConsume
method with
the appropriate paramaters set. The default behaviour is to return ABSTAIN, meaning
the plugin does not handle this type of operation. If a method is overridden, it can then perform
whatever security checks are required and return ALLOWED or DENIED
as appropriate.
public Result authoriseConsume(ObjectType object, ObjectProperties properties);
public Result authorisePublish(ObjectType object, ObjectProperties properties);
public Result authoriseCreate(ObjectType object, ObjectProperties properties);
public Result authoriseAccess(ObjectType object, ObjectProperties properties);
public Result authoriseBind(ObjectType object, ObjectProperties properties);
public Result authoriseUnbind(ObjectType object, ObjectProperties properties);
public Result authoriseDelete(ObjectType object, ObjectProperties properties);
public Result authorisePurge(ObjectType object, ObjectProperties properties);
public Result authoriseExecute(ObjectType object, ObjectProperties properties);
public Result authoriseUpdate(ObjectType object, ObjectProperties properties);
public Result accessVirtualhost(Object instance);
Access Control Security Plugin
This security plugin implements access control using the same configuration file syntax as the
C++ broker. The classes are all in sub-packages of the org.apache.qpid.server.security.access
package. The exposed classes consist of the plugoin itself, its OSGi activator and the configuration
plugin, as well as the properties file and generated code for logging. The private, internal classes,
consist of the ruleset implementation for managing access control list rules. The plugin also makes
extensive use of the enumerations provided by the broker as part of the security plugin interfaces,
for operations, objects and permissions.
Enumerations
These enumerations are used to define exactly what a security plugin can control.
The ObjectProperties
and ObjectProperties.Property
lalala
The ObjectType
The Operation
The Permission
Configuration
Security plugins are configurable using the Qpid XML configuration file, under the <security>
element. This can be either inside the main <broker />
element, as a global plugin affecting
all virtual hosts, or under a <virtualhosts><virtualhost><name>
element, where
the <name>
element is the name of the virtual host that is to be configured. Each security
plugin must register the elements it expects to process using a ConfigurationPlugin
, which is
documented elsewhere.
The plugins are checked in order, first for the virtual host, then globally, and the first ALLOWED or
DENIED response is used.
The ACL configuration file is specified via the contents of the <aclv2>
element. This is simply
the path to the file, which is a plain text format, and is parseable by both Java and C++ brokers. The path can be
specified with embedded property value interpolation, for environment variables or other properties defined in the
configuration file.
${QPID_HOME}/etc/global-security-config.txt
]]>
File Format
The file format is described below.
Whitespace is considered to be any ASCII
byte with a value below 0x20, and is
ignored when it occurs between tokens.
Continuations using the \
character (ASCII 0x5c) are allowed
anywhere on a line, and
can consist of a blank line with a continuation
character as the last non-whitespace token
group group1 name1 name2 \
name3 name4 \
name5
acl allow group1 create queue \
property1 = "value1" \
property2 \
= "value2"
Comments are line-style comments, and any text after
an un-quoted # (ASCII 0x23)
are ignored, including continuations. The #
charater may appear in a quoted string.
Quoted strings consist of any ASCII inside matching pairs of
' or " (ASCII 0x27
and 0x22) characters, including any
otherwise special characters.
Tokens are NOT case sensitive, but quoted
strings ARE.
The = (ASCII 0x3d) character
is special, and is used to indicate property value assignment.
Wildcards are specified using the * (ASCII
0x2a) character in a property value string,
which may be quoted.
Empty lines and lines that contain only whitespace are ignored.
The keyword all is reserved, and matches all individuals,
groups and actions. It may be used in place of a group or
individual name and/or an action - eg acl allow all all,
acl deny all all or acl deny user1 all.
Rules are interpreted from the top of the file down until the
name match is obtained; at which point processing stops.
The last line of the file (whether present or not) will be
assumed to be acl deny all all. If present in the file, any
lines below this one are ignored.
Names and group names may contain only a-z,
A-Z, 0-9,
-, @, /
or _.
Rules must be preceded by any configuration and group definitions they may use;
any name not previously defined as a group will be assumed to be
that of an individual user.
CONFIG lines must have the following tokens in order:
The string literal config
One or more property name-value pairs, in the form property = value
where value is the token true or false
GROUP lines must have the following tokens in order:
The string literal group
The name of the group, which cannot contain @ or
/ characters
A whitespace separated list of user and group names. User names are formatted
as username/domain@realm and group names must have been defined
earlier in the file
ACL rules must have the following tokens in order:
An optional rule number, which should be expressible as a positive Java integer
The string literal acl
The permission, one of allow, allow-log,
deny or deny-log
The name of a single group or individual or the keyword all
The name of an operation, which should be one of consume,
publish, create, access,
bind, unbind, delete,
purge, update, execute
or the keyword all
Optionally, a single object type or the keyword all
Objects allowed are virtualhost, queue,
topic and exchange
Objects allowed are virtualhost, queue,
topic, exchange, link,
route, method and object
If the object is present, then optionally one or more property name-value pairs in the form
property=value. The property and value can be separated from the
= charater by any amount of whitespace, and the calue can be quoted if
it contains special characters or whitespace.
Property values can add the wildcard * character at the end of the string
to indicate that any string beginning with the characters up to the wildcard will match, or
if the wildcard is the only character, that any string will match
This allows a rather looser and more readable style for ACL files,
while still retaining the ability to read the stricter files accepted
by the C++ broker. Bear in mind that the group declarations are to be
deprecated, in favour of an external directory service, using a plugin
mechanism.
The initial number is used to allow rulesets to be created which allow
individual rules to be enabled and disabled using an admin interface,
and an ACL file using numbered lines would be restricted to having
increasing numbers per rule, although gaps would be allowed to enable
rules to be inserted later, again using an admin interface. This
administrative interface would also allow saving of a modified ruleset
and re-loading.
Broker Access Control
The Java broker access control mechanism is used to protect internal
entities used by the broker. These are virtual hosts, queues, topics
and exchanges. The actual access control checks take place in the
methods that carry out the operations on these objects, in order to
ensure thatsecurity is both mechanism and protocol agnostic.
The Java broker does not support LINK
or
ROUTE
object types.
An example of the various rules that can be specified follows:
acl allow robot create exchange name="robot.*"
acl deny kitten create queue
acl allow guest bind exchange name=amq.topic routingkey="kitten.#"
acl allow all create queue name="tmp.*"
acl allow guest publish all durable="false"
acl allow robot create queue name="robot"
acl allow kitten consume queue durable="true"
acl allow guest create all
Management Access Control
The management of the broker using JMX is also protected by the security
plugins, in two ways. If the management interface is used to perform
operations that would be access controlled normally, the same rules
would still apply and be applied. However, this only occurs when the
JMX connection was authenticated. If JConsole is used to connect directly
to a broker process started by the same user, then no extra checks are made.
The management operations themselves are also able to be access controlled.
This is done using the METHOD
object type. A component name
and method name are specified as properties, and these indicate the MBean
type name and JMX method name respectively. If the operation is set to
ALL
then reading JMX attributes, writing JMX attributes and
invoking JMX operations are controlled by the rule. Otherwise, the three
operations ACCESS
, UPDATE
and EXECUTE
control reading, writing and invocation respectively.
ACL ALLOW user ALL METHOD
ACL ALLOW user ALL METHOD name="method"
ACL ALLOW user ALL METHOD name="prefix*"
ACL ALLOW user ALL METHOD component="MBean" name="method"
ACL ALLOW user ACCESS METHOD component="MBean"
ACL ALLOW user UPDATE METHOD component="MBean"
ACL ALLOW user EXECUTE METHOD component="MBean"
External Object Access Control
At the moment the C++ broker has an extension point to allow access control
of external objects. This will be provided in the Java broker as well, using the
ACCESS OBJECT
rule, with package name and class name properties.
The external object must be able to retrieve a reference to the virtual host
it is running on, and then call the accessObject
method. This
must be the responsibility of the external object.
Note that this is not currently implemented in the SecurityManager
.
ACL ALLOW user ACCESS OBJECT package="com.example.application" class="Extension"
if (!_vhost.getSecurityManager().accessObject("com.example.application", "Extension"))
{
// TODO reject access somehow - exception
}
Other Security Plugins
There are two basic plugins provided internally by the broker, which can be
found in the org.apache.qpid.server.security.access.plugins
package.
These are AllowAll
and DenyAll
. The LegacyAccess
plugin is not normally required, and simply ignores legacy elements of the configuration
file. The other two plugins are activated by the presence of an element in the
<security />
section of the configuration or virtual hosts XML
files. To deny all access by default, add the empty <deny-all />
element, and to allow all access, add <allow-all />
.