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Security and
Authentication
Wednesday, May 24, 2017
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Legal Information…
Any statements in this presentation about future
expectations, plans and prospects for the Company, including
statements about the Company, the Building Blocks Program
and other statements containing the words “believes,”
“anticipates,” “plans,” “expects,” “will,” and similar
expressions, constitute forward-looking statements within
the meaning of The Private Securities Litigation Reform Act
of 1995. Actual results may differ materially from those
indicated by such forward-looking statements as a result of
various important factors, including: product development,
and other factors discussed in our Registration Statement
filed on Form S-1 with the SEC. In addition, the forwardlooking statements included in this press release represent
the Company’s views as of July 26, 2004. The Company
anticipates that subsequent events and developments will
cause the Company’s views to change. However, while the
Company may elect to update these forward-looking
statements at some point in the future, the Company
specifically disclaims any obligation to do so. These forwardlooking statements should not be relied upon as representing
the Company’s views as of any date subsequent to July 26,
2004.
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Security – High Level View
Authentication

Who is using the system?
Authorization

Can that user do what they’re trying to do?

Is the users’ data kept private?
Can the code do what it is trying to
Privacy
do?
Integrity

Has the data been tampered with?
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Topics for Extension Developers
Common Security Tasks

Authentication, Authorization
Declaring Permissions

Often trial and error iteration… add a permission, get
stopped by another one
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Overview – Java Security
All Part of JDK 1.4
JSSE – Java Secure Sockets Extension

SSL support, etc.

TLS, RFC-2246
JCE – Java Cryptography Extensions

Pluggable crypto provider framework
Java GSS-API

Java bindings for Generic Security Services API (RFC-2853)
CertPath API

API for examining certificate chains
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Overview – Java Security
JAAS – Java Authentication and Authorization Service

Pluggable Authentication

Authorization for code and principals
Code Security Model

Who can do what

What code can do what
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Language Features
Type safety

Compile-time

Run-time
Byte code verification

Well formed class files

No illegal sequences – e.g., check for stack underflow, etc.
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Authentication for Extensions
Simple, let the platform worry about it…
BbSessionManagerService sessionService =
BbServiceManager.getSessionManagerService();
BbSession bbSession =
sessionService.getSession( request );
AccessManagerService accessManager =
(AccessManagerService)BbServiceManager
.lookupService( AccessManagerService.class );
if (! bbSession.isAuthenticated() ) {
accessManager.sendLoginRedirect(request,response);
return;
}
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Authentication for Extensions
Access Manager coordinates with
authentication providers to do the right
thing
Default providers

RDBMS

LDAP

Web Server
Custom providers
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Authorization in Blackboard
Role-based assignment

System role attached to user
object

Course role attached to
enrollment record
User
SystemRole
*1
1
Privileges attached to Roles

Editable

Check relies on the union of all
relevant entitlements
*
*
Entitlement
**
*
Membership
CourseRole
*1
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Customizing Privileges
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
It All Comes Back To…
Context!

You have the user, and thus the system role…

You have the course, and thus the course role...

Access control works against the full entitlements
mask
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Authorization for Extensions
Authorization

Role-based checks – Deprecated...

Entitlement-based checks – Not finalized…
PlugInUtil.authorizeForXXX()

authorizeForCourseControlPanel()

authorizeForSystemAdminPanel()

authorizeForCourse()

authorizeForContent()
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Code Security Framework
Leverage security inherent in the Java 2
Standard Edition framework
Enforce certain API restrictions
Enforce API usage disclosure

Manifest must declare required permissions
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Code Security – Historical
“Sandbox” model – JDK 1.0

Applets just couldn’t do certain things

Hard to manage/understand
“Trusted” model – JDK 1.1

Permissions assignable to trusted code

Code (applets) could be signed
“Domain” model – JDK 1.2

Policy

Domains
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Basic Class Hierarchy
Principal
+getName()
0..* Has
1
Has
Class
+getProtectionDomain()
1
1
+getCodeSource()
+getPermissions()
1
PermissionCollection
Has
ProtectionDomain
1
1
Permissions
+add()
+implies()
+elements()
Has
Contains
*
0..*
1
CodeSource
Permission
+getCertificates()
+getPermissions()
+implies(in codeSource : CodeSource)
+implies()
+getName()
+getActions()
AllPermission
checks
BasicPermission
PersistPermission
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
SecurityManager
+checkPermission()
Permission Class
Permission

Abstract base class for all permissions

All Permission objects define a name and actions

Relationships can be created via
implies( Permission )
BasicPermission

Concrete base class for most permissions
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Classes
Security information available through Class
object

Object.getClass()
ProtectionDomain

Encapsulates information about the classes physical source
and associated permissions

Class.getProtectionDomain()
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Classes
PermissionCollection

ProtectionDomain.getPermissions()

List of permissions
– PermissionCollection.implies( Permission )
CodeSource

ProtectionDomain.getCodeSource()

Physical location of class (URL)
– Hierarchical: CodeSource.implies( CodeSource )

Certificates
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Security Checks
SecurityManager.checkPermission( Permission )

Other checkXXX() methods ultimately
delegate to this method

This method, in fact, delegates to AccessControlManager
For each frame in call stack

Get code source

Get permissions for code source

Requested permission implied by permissions collection?
SecurityException thrown if check fails
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Checking Permissions
if( _modifyPermission != null )
{
System.getSecurityManager()
.checkPermission( _modifyPermission );
}
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Privileged Blocks
Short-circuit stack walk
If the current frame has permission, allow
access
Allows trusted code to perform actions that
may not be granted to the caller

E.g., un-trusted code may not have network permission, but
the database driver does
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Examples
We do not allow System Extensions to get raw database
connections
Our own code, which may be called by a System
Extension, needs to get a database connection
Solution: Privileged block

Code executing with more privileges can accomplish what it needs to
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Example
private class DbConnectivityPrivilege implements PrivilegedExceptionAction
{
private Query _query;
private Connection _con;
private DbConnectivityPrivilege(Query query, Connection con)
{
_query = query;
_con = con;
}
public Object run() throws Exception
{
_query.executeQuery( _con );
return null;
}
}
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Example
try
{
AccessController.doPrivileged(
new DbConnectivityPrivilege(query, con));
}
catch(PrivilegedActionException pae)
{
castException( pae );
}
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Example
SecurityManager.checkPermission()
Initiates Stack Walk
Query.executeQuery()
DbConnectivityPrivilege.run()
NewBaseDbLoader.loadObject()
AnnouncementDbLoaderImpl.loadById()
ExtensionClass.foo()
ExtensionServlet.service()
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Stack Walk
Call Sequence
ConnectionManager.getConnection()
Terminates Stack Walk
Policies
Policies define the Permissions associated with
code bases
Default implementation uses a policy file
Grant/deny permissions to code bases
Grant/deny permissions to Subjects

Person or Service

New in JDK 1.4 with addition of JAAS
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Example Policy File Entries
Tomcat.policy
// Tomcat gets all permissions
grant codeBase "file:${tomcat.home}${/}lib${/}-" {
permission java.security.AllPermission;
};
grant {
permission java.util.PropertyPermission "java.version", "read";
permission java.util.PropertyPermission "java.vendor", "read";
}
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Activating Security
Run-time properties on the command line

-Djava.security.manager

-Djava.security.policy
java.security – Configuration file for setting
security providers

policy.provider – Class that is responsible for implementing
the policy
– Default is sun.security.provider.PolicyFile
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Blackboard Implementation
wrapper.properties/tomcat.sh

Points to tomcat.policy
service-config.properties

code-level-access-control=true

Can disable SecurityManager regardless of command line
options
Custom Policy implementation
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Blackboard Implementation
SecurityUtil.checkPermission()

Hides check for SecurityManager

Propagates Security Exceptions
BbPolicy

Wraps code sources for System Extensions

Attempts to prevent “over-riding”
– You can’t just put permissions in the policy file
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Blackboard Permissions
blackboard.persist.PersistPermission

Name is the data object, actions are
“read,create,modify,delete”

Base persister and loader classes check for permission
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Blackboard Permissions
blackboard.data.AttributePermission

Controls access to attributes on a data object

Naming convention allows single attributes or groups to be
protected

E.g., untrusted code can load a user, but can’t get the
(hashed) password
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Blackboard Permissions
<permission type=“persist”
name=“Content”
actions=“create,modify,delete”/>
<permission type=“attribute”
name=“user.authinfo” actions=“read,write”/>
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
System Extensions
Deployed as a web application with a unique code source

Code source is attached to /plugin directory, so it encompasses the
/webapp and /config directories
Manifest includes a permissions block

Some filtering to restrict certain permissions

Manifest is equivalent of policy file
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
System Extensions
Enabling an extension at startup

Read permissions from database

Associate with web app code source

Register servlet context with Tomcat
– Registration of servlet context only occurs if extension is
“Available” or “Unavailable”. Otherwise, no code may be executed
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
System Extensions
Permissions block contains 0 or more permission
elements
Same semantics as “grant” entries in the standard Java
policy file

No explicit deny
Simple mnemonics for common types

Runtime, Socket, Persist, Attribute
Type attribute can be any fully qualified Java classname

Must be a Permission sub-class, with two argument constructor
(String, String)
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Default Permissions
Read/write access to extension’s home
directory
Read access to Blackboard root
Read access to data (via APIs)
Read access to system properties
Everything else must be explicitly declared…
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Example Permissions
<permissions>
<permission type=“socket”
name=“api.google.com” actions=“connect”/>
<permission type=“runtime”
name=“accessDeclaredMembers” actions=“”/>
<permission type="java.util.PropertyPermission"
name="java.protocol.handler.pkgs" actions="write"/>
</permissions>
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Manifest Limitations
No escape syntax

Properties that require user input, or information from local
system, cannot be encoded in permission block
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Tips
Read the Javadoc for any third party libraries
you are using

Many developers don’t test their code with a security
manager, so they don’t know what they’re touching
– E.g., Axis configuration routines will throw SecurityException if
run with a SecurityManager
Think security…

What would you as an administrator want to see disclosed?
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Tips – Common Restrictions
System.getProperties()

returns a mutable copy of the system permission; thus you
need
<permission type=“java.util.PropertyPermission”
name=“*” actions=“read,write”/>
Reflection requires runtime permission
Spawning a process requires a runtime
permission
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Conclusion
System Extensions have access to verify both
authentication and authorization
Administrators have an additional level of
disclosure about what extensions will access
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.
Thank You!
Tom Joyce, Blackboard Product Development
[email protected]
Concluding Presentation is at 2PM:
Building Blocks and Blackboard—A Look Ahead
Salon H (Where the keynote was held)
©2004 BLACKBOARD, INC. ALL RIGHTS RESERVED.