The Java security mechanism is quite easy to use. The main classes are:
1) Subject - defines a person - contains several Principals, and has
methods to allow code to be executed as a given Principal.
2) Principal - sort of like a role that a person has. The primary
Principal is the one that defines who a person is, the others are roles
that they have.
3) Permission - used to both grant and verify privileges. The general
usage is something like this:
4) SecurityManager -used to check permissions and run code as a given
user, or to temporarily get extra permissions
5) Policy - defines what a subject, or code is allowed to do, contains
Permission's associated with a given Principal
public void function(Argument a1, Argument a2) {
SecurityManager.checkPermission(new MyPermission("function", a1));
// rest of body to execute function
}
where you have defined MyPermission to be a sub-class of Permission that
takes an operation name ("function" in the example), and some parameters
(if needed.)
Then, you can call this method using code similar to:
Subject subject = (Subject) request.getProperty("Subject");
subject.doAs(subject, new PrivilegedAction() { public Object run() {
function(a1,a2); } };
Generally, the doAs part is handled by the framework as part of a wrapper
around executing action.
The Policy must map Principals to a set of Principals, and then each
principal is checked to see if it can grant "MyPermission".
By default AllPermission grants any permission at all, and since it is only
one permission, it is granted very quickly.
If there are lots of permissions to check, then there are ways to make this
all work very quickly, usually just the cost of a single check permission
call, and a single hash map lookup (Ask me about this only after you
understand the rest of the basic concepts.)
To get a subject, there is generally a DB table that maps login id's to an
array of subjects, and as part of the login process, the Subject is put
into the session object.
Note that this systems is extremely flexible, while also being very easy to
use for minimalist security. You can do things like requiring a new
password to be entered if the user attempts to use certain permissions.
You can also automatically dis-allow JSP or servlet pages to be viewed by
putting checkPermission's into the servlet/JSP page, or else check a
permission and remove a portion of a page based on security settings.
Because there is already a fairly complete policy file parser, you can use
that to start working with permissions, and only change over to a more
complete system later on (or not if it isn't needed.)
Bill Wallace
(716) 214-8872
Fax: (716) 295-4718
Element K
'the knowledge catalyst'
www.elementk.com
"Lacerda,
Wellington (AFIS)" To: "'[EMAIL PROTECTED]'"
<[EMAIL PROTECTED]>
<Wellington.Lacerd cc:
[EMAIL PROTECTED]>
Subject: RE: Extensibility of struts
& Property Security
11/28/01 09:35 AM
I'd like to have more info on that!
Wellington
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 28, 2001 3:29 PM
To: Struts Developers List
Subject: Re: Extensibility of struts & Property Security
Please use the standard java security mechanism, rather than trying to
invent a new one. The standard mechanism is very general, and allows very
fast checks when security is turned off, and conversely, allows very
fine-grained security checks to be made. I have implemented this in a
web-model and it works quite well. Send me email if you want more
information on using it, preferably after you read the java documentation
(look at JAAS).
Bill Wallace
(716) 214-8872
Fax: (716) 295-4718
Element K
'the knowledge catalyst'
www.elementk.com
Arron Bates
<arron@keyboardm To: Struts Developers List
<[EMAIL PROTECTED]>
onkey.com> cc:
11/27/01 08:45 Subject: Re: Extensibility
of
struts & Property Security
PM
Please respond
to "Struts
Developers List"
Yes, yes. Point made.
That series of emails makes for some good bedside reading.
I think that the solution that was arrived at is fine for protecting the
struts system objects themselves.
Is there anything happening to allow the developer to protect their own
properties from this kind of arbitrary attack?
Thought I had would be to configure a property modifier, or property
mapping which yields other "security properties" which have to be
checked before a property is set. ie: getMyProperty() property method
uses a getMyPropertySecurity() to return a defined value which was set
while writing the view so you can't just pass the one key value pair to
change a value, but a two key value pairs with the second value being a
specific hashing or such. This would stop the casual hacking of any
property via the URL. You could also then define a security property for
all things struts within the ActionForm.
The possibility then in extending this would be to define a security
property to each property to be set, or a more simpler global security
property for the entire request, and let the developer decide as to how
fine grained the property setting security should be, if at all.
Just a thought.
Arron.
Ted Husted wrote:
>http://nagoya.apache.org/bugzilla/showattachment.cgi?attach_id=813
>
>"So, someone could also call
>
>getServlet().setTempDir(whatever)
>
>with
>
>http://whatever.com/do/someAction?servlet.tempdir=whatever
>
>Hmmm."
>
>-- Ted Husted, Husted dot Com, Fairport NY USA.
>-- Custom Software ~ Technical Services.
>-- Tel +1 716 737-3463
>-- http://www.husted.com/struts/
>
>
>Arron Bates wrote:
>
>>It doesn't even have to be a careful look at the code. It's not complex
>>in the least.
>>
>>I must be missing something with the "String or boolean properties that
>>affect the system state" thing.
>>
>>Do you mean what it is that I do with the example, where I have a string
>>property that represents a submit button that add objects to the tree
>>and another that can delete them?... If it isn't, can I get an
example?...
>>
>>Arron.
>>
>
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