Difference between revisions of "OAuth for MyProxy GetProxy Endpoint"

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[http://grid.ncsa.illinois.edu/myproxy/oauth/ OAuth for MyProxy] (OA4MP) is based around the [https://docs.google.com/document/d/1cs3peO9FxA81KN-1RC6Z-auEFIwRbJpZ-SFuKbQzS50/pub OIDC/OA4MP Protocol], which is a modified version of [http://openid.net/specs/openid-connect-core-1_0.html OpenID Connect]. The modifications introduced by OA4MP include the [https://docs.google.com/document/d/1cs3peO9FxA81KN-1RC6Z-auEFIwRbJpZ-SFuKbQzS50/pub#h.3khs91kr9igo GetCert Endpoint] which is used by the OA4MP Client (ex. Science Gateway) to retrieve an End Entity Certificate (EEC) on behalf of the authenticated user. In certain scenarios the use of EECs can be replaced by Proxy Certificates. Proxy Certificates, usually having a shorter lifetime than EECs, are less likely to be used maliciously given their short validity period, while still conveying the same authentication information as an EEC would. Moreover, a Proxy Certificate can contain additional authorization information in the form of VOMS Extensions.   
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[http://grid.ncsa.illinois.edu/myproxy/oauth/ OAuth for MyProxy] (OA4MP) implements the [http://goo.gl/VnMKXS OIDC/OA4MP Protocol], which is an extension of the [http://openid.net/specs/openid-connect-core-1_0.html OpenID Connect] specification. The modifications introduced by OA4MP on top of OIDC include the [http://goo.gl/VnMKXS#h.3khs91kr9igo GetCert Endpoint] which is used by the OA4MP Client (e.g. a Science Gateway) to retrieve an End Entity Certificate (EEC) on behalf of the authenticated user. Typical workflows on the other hand usually do not directly make use of EECs, but instead use [https://tools.ietf.org/html/rfc3820 RFC3820] Proxy Certificates.<br>
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Proxy Certificates, usually having a shorter lifetime than EECs, are less likely to be used maliciously given their short validity period, while still conveying the same authentication information as an EEC would. Moreover, a Proxy Certificate can contain additional authorization information in the form of VOMS Extensions.   
  
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We propose adding a GetProxy Endpoint into the OIDC/OA4MP Protocol, which returns Proxy Certificates. The main differences between the GetProxy and GetCert Endpoint are:
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The AARC-developed MasterPortal therefore adds a GetProxy Endpoint to the OIDC/OA4MP Protocol, which directly returns Proxy certificate chains to its clients. The main differences between the GetProxy and GetCert Endpoint are:
  
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* returns Proxy Certificates
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* return RFC3820 Proxy Certificate chain
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* generates CSR on server side instead of client side
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* generates keypair and CSR on server side instead of client side
 
* accepts VONAME and VOMSES parameters  
 
* accepts VONAME and VOMSES parameters  
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For the ''technical implementation details'' of the Getproxy Endpoint, see [[OAuth_for_MyProxy_GetProxy_Endpoint_-_Implementation | here]].
  
 
== Protocol Specification ==
 
== Protocol Specification ==
  
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The GetProxy Endpoint, just like the GetCert Endpoint is an OAuth2.0 protected resource that returns a proxy certificate. This proxy certificate consists of a certificate chain and private key of the proxy. The request made to the GetProxy Endpoint is made up of the following parameters:
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The GetProxy Endpoint, just like the GetCert Endpoint, is an OAuth2.0 protected resource that returns a proxy certificate. This proxy certificate consists of a certificate chain and private key of the proxy. The request made to the GetProxy Endpoint is made up of the following parameters:
  
 
{| class="wikitable" style="width: 55%;"
 
{| class="wikitable" style="width: 55%;"
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|-
 
|-
 
| style="width: 25%;" | client_id
 
| style="width: 25%;" | client_id
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| style="width: 33%;" |REQUIRED if not provided in <br />HTTP Basic Authorization header
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| style="width: 33%;" |REQUIRED
 
| The client identifier issued at registration time.
 
| The client identifier issued at registration time.
  
 
|-
 
|-
 
| style="width: 25%;" |client_secret
 
| style="width: 25%;" |client_secret
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| style="width: 33%;" |REQUIRED if not provided in <br />HTTP Basic Authorization header
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| style="width: 33%;" |REQUIRED
 
| The client secret issued at registration time.
 
| The client secret issued at registration time.
  
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| style="width: 25%;" |voname
 
| style="width: 25%;" |voname
 
| style="width: 33%;" |OPTIONAL
 
| style="width: 33%;" |OPTIONAL
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| Specifies one or more VO to connect to for membership information. The VO name can be followed by additional group and role request. (see 'man voms-proxy-init' under -voms)
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| Specifies one or more VOs to connect to for membership information. The VO name can be followed by additional groups and roles. (Same format as for the ''-voms'' option to ''voms-proxy-init'', see ''man voms-proxy-init'').
  
 
|-
 
|-
 
| style="width: 25%;" |vomses
 
| style="width: 25%;" |vomses
 
| style="width: 33%;" |OPTIONAL
 
| style="width: 33%;" |OPTIONAL
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| Specifies VOMS server information under 'vomses' file format
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| Specifies VOMS server information in 'vomses' file format.
  
 
|}
 
|}
  
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Just like in case of GetCert, the access_token, client_id and client_secret parameters are there to ensure the authenticity of the request. Note that the 'certreq' parameter, containing the Certificate Signing Request (CSR), is no longer sent along in the request. Instead, a new keypair and CSR are created on the server side and used in the subsequent MyProxy GET request. The motivation behind this change is to take the burden of key generation off the OA4MP Client, thus making it more lighweight and easily adaptable by different communities.
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Just as for the GetCert endpoint, the access_token, client_id and client_secret parameters are there to ensure the authenticity of the request. Note that the 'certreq' parameter (of the getcert request), containing the Certificate Signing Request (CSR), is not required. Instead, a new keypair and CSR are created on the server side and used in the subsequent MyProxy GET request. The motivation behind this change is to take the burden of key generation away from the OA4MP Client, thus making it more lightweight and easier to adopt by different communities.
  
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Requesting a VOMS Proxy Certificate can be done by using the 'voname' and 'vomses' request parameters. These parameters are passed as they are to the subsequent [http://grid.ncsa.illinois.edu/myproxy/protocol/ MyProxy GET] request.
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Requesting a VOMS Proxy Certificate can be done by using the 'voname' and 'vomses' request parameters. These parameters are passed as-is to the [http://grid.ncsa.illinois.edu/myproxy/protocol/ MyProxy GET] request executed by the MasterPortal.
  
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'''Note:''' The VOMSES string is useful in scenarios where the user would like to get membership information from a VOMS server which is not configured in the backend MyProxy Server 'vomses' file.
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'''Note:''' The VOMSES string is useful in scenarios where the client would like to make use of a VOMS server which is not configured locally in the back-end MyProxy Server (in its 'vomses' file, see 'man myproxy-server.config' under 'voms_userconf').
  
 
=== Example Request ===
 
=== Example Request ===
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POST Example
 
POST Example
  
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  POST /getcert HTTP/1.1
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  POST /getproxy HTTP/1.1
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  Host: myproxy.example.edu
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  Host: masterportal.example.edu
 
  Content-Type: application/x-www-form-urlencoded
 
  Content-Type: application/x-www-form-urlencoded
 
   
 
   
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  voname=superscience&vomses=%22testvo%22%20%22voms.example.edu%22%20%2215000%22%20%22%2FC%3DXX%2FO%3DExample%2FCN%3Dmyproxy.example.edu%22%20%22testvo%22
 
  voname=superscience&vomses=%22testvo%22%20%22voms.example.edu%22%20%2215000%22%20%22%2FC%3DXX%2FO%3DExample%2FCN%3Dmyproxy.example.edu%22%20%22testvo%22
  
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  curl --capath /etc/grid-security/certificates/ -H "Host: myproxy.example.edu" -H "Content-Type: application/x-www-form-urlencoded" -X POST -d \
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  curl --capath /etc/grid-security/certificates/ -d \
 
       'client_id=s6BhdRkqt3&client_secret=some_secret12345&access_token=8xLOxBtZp8&proxylifetime=43200&
 
       'client_id=s6BhdRkqt3&client_secret=some_secret12345&access_token=8xLOxBtZp8&proxylifetime=43200&
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       voname=superscience&vomses="testvo" "voms.example.edu" "15000" "/C=XX/O=Example/CN=myproxy.example.edu" "testvo"' \  
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       voname=superscience&vomses="testvo" "voms.example.edu" "15000" "/C=XX/O=Example/CN=myproxy.example.edu" "testvo"' \
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      https://myproxy.example.edu/oauth2/getproxy
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      https://masterportal.example.edu/oauth2/getproxy
  
 
=== Example Response ===
 
=== Example Response ===
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  -----END CERTIFICATE-----
 
  -----END CERTIFICATE-----
  
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== Implementation Details ==
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=== Example client code ===
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The implementation of the GetProxy Endpoint has been separated from the Master Portal OA4MP extension because it was found to be much easier to modify existing OA4MP code than to extend it. This basically means that for the purpose of implementing this endpoint we forked OA4MP. This custom OA4MP having the GetProxy Endpoint implemented can be found under the [https://github.com/ttomttom/myproxy-fork myproxy-fork] and [https://github.com/ttomttom/ncsa-security-all-fork/ ncsas-security-all-fork] projects. The separation of the two codebases is inherited from the original OA4MP implementation.
 
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=== myproxy ===
 
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==== Client ====
 
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The OA4MP Client has to be able to distinguish between cases of requesting an EEC through GetCert and requesting a proxy through GetProxy, since the backend [[#Server|Server]] is configured to provide one '''OR''' the other (EEC or Proxy), '''not both'''. This is done with the use of a new [http://grid.ncsa.illinois.edu/myproxy/oauth/client/manuals/parameters.xhtml#tags OA4MP Client configuration] parameter called 'requestProxies'.
 
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{| class="wikitable" style="width: 55%;"
 
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|-
 
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|
 
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| Required?
 
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| Default
 
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| Description
 
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|-
 
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| requestProxies
 
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| N
 
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| false
 
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| Enables making requests to the GetProxy Endpoint
 
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|}
 
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Configuration example:
 
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<client name="client-config" address="https://portal.example.edu/portal">
 
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    ...
 
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          <requestProxies>true</requestProxies>
 
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    ...
 
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</client>
 
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By setting this configuration to '''true''' a GetProxy Endpoint aware ''OA2MPProxyService'' object will be returned to client servlets instead of a ''OA2MPService'' object. The servlet can then request a proxy by calling the ''getProxy(OA2Asset a, ATResponse2 atResponse2)'' method of the returned object. The [[#Example Request|GetProxy request]] is build internally using the clients' ID, secret and the current transactions' access token. User input (voname and vomses) should be provided to this method via the ''OA2Asset'' parameter. The proxylifetime parameter is taken from the 'lifetime' client configuration.
 
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==== Server ====
 
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The OA4MP Server has both GetCert and GetProxy Endpoints available at the same time, but the MyProxy Server in its backend can only be configured to return '''either''' EEC '''or''' Proxy Certificate. Therefore caution must be taken to only expose the GetProxy Endpoint in case the backend MyProxy is configured to issue Proxy Certificates, otherwise you will end up getting EECs from the GetProxy Endpoint instead of the desired proxy.
 
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'''Note:''' Do not use the GetProxy Endpoint when the backend MyProxy Server is configured as a CA issuing End Entity Certificates!
 
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The implementation of the GetProxy servlet is done in ''OA2ProxyServlet''. A successful GetProxy request will execute the following flow in the servlet:
 
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[[File:Getproxy_servlet_seq.svg? ]]
 
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* Step 1 : As mentioned above, the key and CSR generation has been moved away from the OA4MP Client into the Server. The ''verifyAndGet'' method creates a new keypair and saves the resulting private key and CSR into the transaction. The proxylifetime, voname and vomses are also stripped off here from the request and saved in the transaction.
 
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* Step 2 : The ''checkMPConnection'' method initiates a new MyProxy connection
 
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* Step 3 : The ''getX509Certificates'' method inserts the proxylifetime, voname and vomses values into the MyProxy connection after which proceeds to execute a MyProxy GET command, returning the certificate chain created.
 
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* Step 4 : The ''preprocess'' method is called before the resulting certificate chain is written out into the response buffer. Here, the ''MyX509Certificates'' holding only the certificate chain is swapped out to a ''MyX509Proxy'' object containing the same certificate chain, together with the private key from the transaction (saved in Step 1).
 
  
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=== ncsa.security.all ===
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For example code, see this [https://rcdemo.nikhef.nl/demobasic/ simple PHP demonstrator], which shows how the <tt>/getproxy</tt> endpoint can be used to obtain a valid proxy certificate.

Revision as of 10:11, 5 September 2019

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