The Fedora WebAC authorization Fedora module is an implementation of the W3C's still evolving draft by the W3C that proposes a of an RDF-based decentralized authorization mechanism. See WebAccessControl specifications at the W3C website. policy mechanism.

W3C's definition of WebAccessControl

From the WebAccessControl description at the W3C website:

WebAccessControl is a decentralized system for allowing different users and groups various forms of access to resources where users and groups are identified by HTTP URIs.

...

The WebAC module will enforce access control based on the Access Control List (ACL) RDF resource associated with the requested resource. The ACL resource should specify the types of access, allowed users or groups, and applicable resources.

User -> Read/Write/Append/Control -> Resource/ResourceType

Example:

...

In WebAC, an ACL consists of a set of Authorizations. Each Authorization is a single rule for access, such as "users alice and bob may write to resource foo", described with a set of RDF properties. Authorizations have the RDF type http://www.w3.org/ns/auth/acl#Authorization.

For the remainder of this document, the http://www.w3.org/ns/auth/acl# namespace will be abbreviated with the prefix acl:.

Authorizations

The properties that may be used on an acl:Authorization are:

Property	Meaning
`acl:accessTo`	the URI of the protected resource
`acl:agent`	the user (in the W3C WebAC ontology, the user is named with a URI, but Fedora's implementation supports both URI- and string-based usernames)
`acl:mode`	the type of access (WebAC defines several modes: `acl:Read`, `acl:Write`, `acl:Append`, and `acl:Control`; Fedora implements `acl:Read` and `acl:Write`)
`acl:accessToClass`	an RDF class of protected resources
`acl:agentClass`	a group of users (defined as a `foaf:Group` resource listing its users with the `foaf:member` property)

For a more detailed explanation of Authorizations and their properties, see WebAC Authorizations.

Examples of Authorizations

The user userA can Read document foo
Code Block
language text
@prefix acl: <http

...

://www.w3.org/ns/auth/

...

acl#>

<> a acl:Authorization ;
    acl:accessTo </foo> ;

...

acl:mode acl:Read;

...

acl:agent

...

"userA" .

...

Users in NewsEditor group can Write to any resource of type ex:News
Code Block
language text
@prefix acl:

...

<http://www.w3.org/ns/auth/

...

acl#> .
@prefix ex: <http://example.org/ns#> .

<> a acl:Authorization ;
    acl:accessToClass ex:News ;
    acl:mode acl:Read, acl:Write;

...

acl:agentClass </agents

...

/NewsEditor> .

Code Block

language	text
title	/agents/NewsEditors

@prefix foaf: <http://xmlns.com/foaf/0.1/> .

<> a foaf:Group;
    foaf:member "editor1", "editor2".

The user userB can Read document foo (This involves setting a system property for the servlet container, e.g. -Dfcrepo.auth.webac.userAgent.baseUri=http://example.org/agents/)
Code Block
language text
@prefix acl: <http://www.w3.org/ns/auth/acl#> <> a acl:Authorization ; acl:accessTo </foo> ; acl:mode acl:Read; acl:agent <http://example.org/agents/userB> .

Storing WebAC ACLs in Fedora 4

In Fedora 4, an ACL is a ldp::BasicContainer resource with the additional RDF type of http://fedora.info/definitions/v4/webac#Acl. This class is part of the Fedora WebAC ontology. Its children should each be resources of type acl:Authorization. It is given the namespace prefix webac: by convention.

Protecting Resources

A resource specifies the location of its ACL using the acl:accessControl property. If a resource itself does not specify an ACL, its parent containers are inspected, and the first specified ACL found is used as the ACL for the requested resource. If no ACLs are found, a filesystem-based ACL will be checked, the default policy of which is to deny access to the requested resource.

Example Scenarios

These scenarios assume that Fedora has been configured to use fcrepo.auth.webac.userAgent.baseUri=http://example.org/agent/ and fcrepo.auth.webac.groupAgent.baseUri=http://example.org/group/

Example Request Authorization Flow:

...

I want to allow a user with username "smith123" to have have read, write access to resource http://localhost:8080/rest/webacl_box1.

Expand
Using

these

the two "files" below to create our Authorization and ACL resources.

Code Block

title	Acl.ttl

@prefix

rdf

webac: <http://

www

fedora.

w3.org

info/

1999

definitions/

02/22-rdf-syntax-ns#> . @prefix ldp: <http://www.w3.org/ns/ldp#>

v4/webac#> .
<> a

ldp:BasicContainer ; rdf:type ???:WebAcl

webac:Acl .

Code Block

title	Authorization.ttl

@prefix acl: <http://www.w3.org/ns/auth/acl#> .

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix ldp: <http://www.w3.org/ns/ldp#> .

<> a

ldp:RDFSource ; rdf:type

 acl:Authorization ;
   acl:agent

"smith123"

<http://example.org/agent/smith123> ;
   acl:mode acl:Read, acl:Write ;
   acl:accessTo <http://localhost:8080/rest/webacl_box1> .

We would execute the following commands.

Code Block
> curl -X

POST

PUT -H "Content-type: text/turtle" --data-binary "@Acl.ttl" "http://localhost:8080/rest"

http://localhost:8080/rest/acl

> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Authorization.ttl" "http://localhost:8080/rest/acl/auth1"

http://localhost:8080/rest/acl/auth1

> echo "PREFIX acl: <http://www.w3.org/ns/auth/acl#>
INSERT

INTO

DATA {
<> acl:accessControl <http://localhost:8080/rest/acl> .
}" | curl -X PATCH -H "Content-type: application/sparql-update" --upload-file - "http://localhost:8080/rest/webacl_box1"

I want to let the group "Editors" have have read, write access on all the items in the collection "http://localhost:8080/rest/box/bag/collection"

Expand
Using the

below

two "files"

,

below to create our Authorization and ACL resources.

Code Block

title	Acl.ttl

@prefix

rdf

webac: <http://

www

fedora.

w3.org

info/

1999

definitions/

02/22-rdf-syntax-ns#> . @prefix ldp: <http://www.w3.org/ns/ldp#>

v4/webac#> .
<> a

ldp:BasicContainer ; rdf:type ???:WebAcl

webac:Acl .

Code Block

title	Authorization.ttl

@prefix acl: <http://www.w3.org/ns/auth/acl#>

. @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix ldp: <http://www.w3.org/ns/ldp#>

 .
<> a

ldp:RDFSource ; rdf:type

 acl:Authorization ;
   acl:agent

"Editors"

<http://example.org/group/Editors> ;
   acl:mode acl:Read, acl:Write ;
   acl:accessTo <http://localhost:8080/rest/box/bag/collection> .

We would execute the following commands.

Code Block

> curl -X POST -H "Content-type: text/turtle" --data-binary "@Acl.ttl" "http://localhost:8080/rest"

http://localhost:8080/rest/acl

> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Authorization.ttl" "http://localhost:8080/rest/acl/auth1"

http://localhost:8080/rest/acl/auth1

> echo "PREFIX acl: <http://www.w3.org/ns/auth/acl#>
INSERT

INTO

DATA {
<> acl:accessControl <http://localhost:8080/rest/acl> .
}" | curl -X PATCH -H "Content-type: application/sparql-update" --upload-file - "http://localhost:8080/rest/box/bag/collection"

I would like the collection http://localhost:8080/rest/dark/archive to be viewable only by the groupId "Restricted", but I would like to allow anyone to view the resource http://localhost:8080/rest/dark/archive/sunshine.

Expand
Using the

below

three "files

to setup the Acl and Authorization

" below to create our Authorization and ACL resources.

Code Block

title	Acl.ttl

@prefix

rdf

webac: <http://

www

fedora.

w3.org

info/

1999

definitions/

02/22-rdf-syntax-ns#>

v4/webac#> .
<> a webac:Acl .

Code Block

title	Auth_restricted.ttl

@prefix

ldp

acl: <http://www.w3.org/ns/auth/

ldp#>

acl#> .
<> a

ldp

acl:

BasicContainer

Authorization ;

rdf:type

???:WebAcl

.

Code Block

title	Auth_restricted.ttl

@prefix

acl:agent <http://

www

example.

w3.

org/

ns/auth/acl#> . @prefix rdf:

group/Restricted> ;
   acl:mode acl:Read ;
   acl:accessTo <http://

www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix ldp

localhost:8080/rest/dark/archive> .

Code Block

title	Auth_open.ttl

@prefix acl: <http://www.w3.org/ns/auth/

ldp#>

acl#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<> a

ldp:RDFSource ; rdf:type

 acl:Authorization ;
   acl:agent

"Restricted"

foaf:Agent ;
   acl:mode acl:Read ;
   acl:accessTo <http://localhost:8080/rest/dark/

archive> .

Code Block

title	Auth_open.ttl

archive/sunshine> .

The I would execute the following commands.

Code Block

> curl -X POST -H "Content-type: text/turtle" --data-binary "@Acl.ttl" "http://localhost:8080/rest"

http://localhost:8080/rest/acl_lock

> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Auth_restricted.ttl" "http://localhost:8080/rest/acl_lock/auth1"

http://localhost:8080/rest/acl_lock/auth1

> echo "PREFIX

@prefix

 acl: <http://www.w3.org/ns/auth/acl#>
INSERT

. @prefix rdf

DATA {
<> acl:accessControl <http://localhost:8080/rest/acl_lock> .
}" | curl -X PATCH -H "Content-type: application/sparql-update" --upload-file - "http://localhost:8080/rest/dark/archive"

> curl -X POST -H "Content-type: text/turtle" --data-binary "@Acl.ttl" "http://localhost:8080/rest"

http://localhost:8080/rest/acl_open

> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Auth_open.ttl" "http://localhost:8080/rest/acl_open/auth2"

http://localhost:8080/rest/acl_open/auth2

> echo "PREFIX acl: <http://www.w3.org

/1999/

/ns/auth/acl#>
INSERT DATA {
<> acl:accessControl <http://localhost:8080/rest/acl_open> .
}" | curl -X PATCH -H "Content-type: application/sparql-update" --upload-file - "http://localhost:8080/rest/dark/archive/sunshine"

The collection http://localhost:8080/rest/public_collection should be readable by anyone but only editable by users in the group Editors.

Expand

Using the three "files" below to create our Authorization and ACL resources.

Code Block

title	Acl.ttl

@prefix webac: <http://fedora.info/definitions/v4/webac#> .
<> a webac:Acl .

Code Block

title	Auth1.ttl

@prefix acl

02/22-rdf-syntax-ns#> . @prefix ldp

: <http://www.w3.org/ns/auth/

ldp#>

acl#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<> a

ldp:RDFSource ; rdf:type

 acl:Authorization ;
   acl:agent foaf:Agent ;
   acl:mode acl:Read ;
   acl:accessTo <http://localhost:8080/rest/public_collection> .

Code Block

title	Auth2.ttl

@prefix acl: <http://www.w3.org/ns/auth/acl#> .
<> a acl:Authorization ;
   acl:agent

foaf:Agent

<http://example.org/group/Editors> ;
   acl:mode acl:Read, acl:Write ;
   acl:accessTo <http://localhost:8080/rest/

dark/archive/sunshine>

public_collection> .

The

I would execute the following

commands.

code:

Code Block
> curl -X POST -H "Content-type: text/turtle" --data-binary "@Acl.ttl" "http://localhost:8080/rest" http://localhost:8080/rest/acl

_lock



> curl -X PUT -H "Content-type: text/turtle" --data-binary "

@Auth_restricted

@Auth1.ttl" "http://localhost:8080/rest/acl

_lock

/auth1"

http://localhost:8080/rest/acl

_lock/auth1

/auth1

> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Auth2.ttl" "http://localhost:8080/rest/acl/auth2"

http://localhost:8080/rest/acl/auth2

> echo "PREFIX acl: <http://www.w3.org/ns/auth/acl#>
INSERT

INTO

DATA {
<> acl:accessControl <http://localhost:8080/rest/

acl_lock>

acl> .
}" | curl -X PATCH -H "Content-type: application/sparql-update" --upload-file - "http://localhost:8080/rest

/dark/archive"

/public_collection"

Only the ex:publicImage type objects in the container http://localhost:8080/rest/mixedCollection are viewable by anyone, all others are only viewable by the group Admins.

Expand

Using the three "files" below to create our Authorization and ACL resources.

Code Block

title	Acl.ttl

@prefix webac: <http://fedora.info/definitions/v4/webac#> .
<> a webac:Acl .

Code Block

title	Auth_restricted.ttl

@prefix acl: <http://www.w3.org/ns/auth/acl#> .
<> a acl:Authorization ;
   acl:agent <http://example.org/group/Admins> ;
   acl:mode acl:Read ;
   acl:accessTo <http://localhost:8080/rest/mixedCollection> .

Code Block

title	Auth_open.ttl

@prefix acl: <http://www.w3.org/ns/auth/acl#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
<> a acl:Authorization ;
   acl:agent foaf:Agent ;
   acl:mode acl:Read ;
   acl:accessToClass ex:publicImage .

I would execute the following commands:

Code Block
> curl -X POST -H "Content-type: text/turtle" --data-binary "@Acl.ttl" "http://localhost:8080/rest" http://localhost:8080/rest/acl

_open



> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Auth_restricted.ttl" "http://localhost:8080/rest/acl/auth1"

http://localhost:8080/rest/acl/auth1

> curl -X PUT -H "Content-type: text/turtle" --data-binary "@Auth_open.ttl" "http://localhost:8080/rest/acl

_open

/auth2"

http://localhost:8080/rest/acl

_open

/auth2

> echo "PREFIX acl: <http://www.w3.org/ns/auth/acl#>
INSERT

INTO

DATA {
<> acl:accessControl <http://localhost:8080/rest/

acl_open>

acl> .
}" | curl -X PATCH -H "Content-type: application/sparql-update" --upload-file - "http://localhost:8080/rest/

dark/archive/sunshine"

...

mixedCollection"

Page tree

Versions Compared

Old Version 11

New Version Current

Key

W3C's definition of WebAccessControl

Example:

Authorizations

Examples of Authorizations

Storing WebAC ACLs in Fedora 4

Protecting Resources

Example Scenarios

Example Request Authorization Flow:

How-To Guides

More Detailed Documentation

Page tree

Page History

Versions Compared

Old Version 11

New Version Current

Key

W3C's definition of WebAccessControl

Example:

Authorizations

Examples of Authorizations

Storing WebAC ACLs in Fedora 4

Protecting Resources

Example Scenarios

Example Request Authorization Flow:

How-To Guides

More Detailed Documentation