Access Control In Sun Java System Web Server 7.0

Access Control In Sun Java System Web Server 7.0

You can now download Sun Java System Web Server 7.0 for FREE from http://www.sun.com/download/index.jsp?cat=Web%20%26%20Proxy%20Servers&tab=3&subcat=Web%20Servers .

What Is Access Control?

Access control allows us to determine and manage

  • Who (subject) can access the resources on our web site
  • Which resources (like files or directories)  they can access
  • Which operations can they perform (like creating a file, POST-ing contents to the server).

We can allow or deny access based on:

  • Who is making the request (for example, user or group using user, group attributes).
  • Where the request is coming from (for example, host or IP using ip, dns attributes).
  • When the request is happening (for example, time of day or day of week using timeofday, dayofweek attributes).
  • What type of connection is being used (for example, SSL using ssl attribute).
Authentication is the process of acquiring and verifying the attributes of the subject which help to identify the subject. For example, authentication may involve prompting the user to login with a username and password, and then looking in a database to verify that the user's password is correct.

Authorization is the process of checking the rights (or permissions) to the server resource that are allowed for the subject. for example, a subject might be allowed read access but not write access to a server resource.

An access control entry (ACE) specifies the rules for accessing a given server resource. There are two kinds of ACEs
  • Authentication ACE defines how subject(who is making the request) is identified. It can be used to set authorization method (Digest, Basic, SSL) or database names (like default, myldap, mykeyfile).
  • Authorization ACE defines the rights allowed or denied for a particular subject or a group of subjects.
ACL (Access Control List) is an ordered list of ACEs. An ACL can contain both types of ACEs.

We can control access to the entire server or to parts of the server, or the files or directories on our web site.  When the server gets a request for a page, the server uses the rules in the ACL file to determine if it should grant access or not. We create a hierarchy of rules (called ACEs) to allow or deny access. Each ACE specifies whether or not the server should check the next ACE in the hierarchy. The collection of ACEs we create is called an access control list (ACL).

Types Of ACLs

  • Named ACLs
  • URI (Uniform Resource Indicator) ACLs specify a directory or file relative to the server’s document root.
  • Path ACLs specify an absolute path to the resource they affect.
Path and URI ACLs can include wildcards at the end of the entry. For example: /a/b/\*. Wildcards placed anywhere except at the end of the entry will NOT work.

Examples of Named ACLs

Named ACLs are ACLs which have the first line like acl "<name>"; . It MUST have a corresponding check-acl SAF entry in obj.conf. For example, named acl default or named ACL dav-src  for WebDAV requests we add in Object named dav.

#default.acl
version 3.0;
acl "default";
authenticate (user, group) {
  prompt = "Sun Java System Web Server";
};
allow (read, execute, info) user = "anyone";
allow (list, write, delete) user = "anyone";
...
acl "dav-src";
deny (all) user = "anyone";

Named ACL default  has a corresponding check-acl SAF in obj.conf.  Named ACL dav-src has a corresponding check-acl SAF in obj.conf.

#obj.conf
<Object name=default>
...
PathCheck fn="uri-clean"
PathCheck fn="check-acl" acl="default"
...
</Object>
...
<Object name="dav">
PathCheck fn="check-acl" acl="dav-src"
Service fn="service-dav" method="(GET|HEAD|POST|PUT|DELETE|COPY|MOVE|PROPFIND|PROPPATCH|LOCK|UNLOCK|MKCOL)"
</Object>

Examples of URI based ACLs

URI based ACLs start with uri= prefix. We can set ACLs for a particular resource or a directory and resources inside it. For example, we can set URI based ACL for a particular file file.html

#default.acl
....
acl "uri=/dir1/file.html";
authenticate (user,group) {
  method = "basic";
  database = "myldap";
};
deny (all) user = "anyone";
allow (all) user = "beta";

For setting a URI based ACL on a directory and all the files inside that directory, we can set ACEs like

#default.acl
...
acl "uri=/dir1/\*";
allow (all) dns=".sun.com";
Or
#default.acl
...
acl "uri=/dir1/";
deny (read) user="anyone";
allow (read) group="premium" and dayofweek="Sat,Sun";

Example of Path based ACLs

Path based ACLs start with  "path=" prefix.

#default.acl
...
acl "path=/opt/Sun/Servers/docs/index.html";
deny (read) user="anyone";
allow (read) timeofday<0800 or timeofday=1700;


The URI or path that preceeds the wildcard does NOT work properly if the URI or path information is not a directory but is, instead, a file. For example, the following ACL settings work. When /test/README is accessed, access is allowed only for the user abc.

#default.acl
...
acl "uri=/test/\*";
authenticate (user) {
  prompt = "Test ACL.";
};
deny (all) user = "anyone";
allow (all) user = "abc";

But, the following ACL settings do NOT work. When /test/README is accessed the request is allowed to everyone.

#default.acl
...
acl "uri=/test/READ\*";
authenticate (user) {
  prompt = "Test ACL.";
};
deny (all) user = "anyone";
allow (all) user = "abc";


Only tailing "/\*" is supported in ACL file. ACLs with patterns XX\*, \*XXX\* are ignored. For such scenarios, declare it as a named ACL in obj.conf. For example,

#obj.conf
...
PathCheck fn="check-acl" fn=check-acl path="/pathtosomedir/tes\*.html" acl="acl123"
...
Or
#obj.conf
...
<Object ppath="/pathtosomedir/tes\*.html" >
PathCheck fn="check-acl" acl="acl123"
</Object>

\*\* Note that check-acl usage has a limitation as ACLs are cached in memory. As long as the same ACLs are applied for a resource it is ok. You can not use check-acl for the case where different ACLs are supposed to be added for different condition. For a particular resource we have in obj.conf , <If $client-ip="1.1.1.1"> PathCheck fn="check-acl" acl="acl123" </If> it may or may not add this ACL depending on client's ip address. To make it work we have to disable acl-cache in server.xml (in Web Server 7.0 onwards).

One tip, whenever you want to set an ACL to allow access of a resource to a small audience, first add a deny ACE that would restrict the whole audience from accessing the resource and then add specific ACEs to allow access to the resource to the smaller audience. Something like
#default.acl
...
acl ...
deny (all) user ="anyone";
allow (all) user="alpha,beta,gamma";
Or if you want to add allow ACE first use "absolute" keyword.
#default.acl
...
acl ...
allow absolute (all) user="alpha,beta,gamma";
deny (all) user ="anyone";
Refer my next blog for more information about this.
Comments:

Thank you for the information! Wonderful.

Posted by guest on November 02, 2007 at 05:18 PM IST #

If I am adding a uri-based acl, for instance:

acl "uri=/temp/test1/test2/\*";
allow (list, read, execute, info) user = "anyone";

Do I need a corresponding SAF in the obj.conf? I have done some testing and it seems to work as expected without one.

BTW, this is a great blog, I use it frequently.

Posted by Darren on October 07, 2008 at 01:11 PM IST #

No, you need not add SAF for uri or path based ACLs only name based ACLs needs check-acl SAF to be added in obj.conf.

Thanx for using our Web Server and using my blogs. If you need information on anything else let us know in our Forum http://forums.sun.com/forum.jspa?forumID=759

Posted by Meena on October 07, 2008 at 04:41 PM IST #

thank you for informations, very helpfull!
is there a CLI or WebInterface to add the PathCheck to the obj-conf?

Posted by ivo on January 14, 2009 at 10:59 AM IST #

I am not good in Admin area. In Web Server 7.0, you can manually modify ACL file (and other configuration files) and do a pull-config from Admin CLI/GUI.

Posted by meena on January 15, 2009 at 03:51 AM IST #

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