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https://issues.apache.org/jira/browse/HADOOP-12082?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14700316#comment-14700316
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Larry McCay commented on HADOOP-12082:
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I've applied the patch, built it and given it a quick review.
The implementation seems fine for very specific usecase of HTTP Basic auth
against an LDAP server.
IMO, the coupling of credential scraping: pulling the credentials from the in
coming request and a particular backend implementation like LDAP is unfortunate
and should be reconsidered and refactored in a follow up patch. As I have
described earlier, we should be able to scrape the same credentials from the
request and use them against: LDAP, RDMS or some proprietary auth server. I
think that this refactoring would require separating the current handler for
Ldap into two things:
1. scheme handler
2. authentication handler
{code}
basic.authentication.handler=ldap
{code}
Using the above configuration, we could load all implementations of the
UsernamePasswordAuthenticationHandler interface with the Java ServiceLoader and
interrogate each one for its name. When you find the one that matches the
configured value then it gets used to authenticate the username and password
against its specific backend.
This would allow us to use the same UsernamePasswordAuthenticationHandler for
other ways to get username and password and to use other implementations for
different backends.
The kerberos handler doesn't need this decoupling as far as I can tell.
Unfortunately, I don't think that I am going to be able to leverage this work
for introducing WebSSO flows. Browsers only have the four well known schemes to
work with and will behave according to those schemes upon getting the list of
WWW-Authorization headers. I would love to use this so that we could avoid the
AltKerberosAuthenticationHandler but don't see how.
> Support multiple authentication schemes via AuthenticationFilter
> ----------------------------------------------------------------
>
> Key: HADOOP-12082
> URL: https://issues.apache.org/jira/browse/HADOOP-12082
> Project: Hadoop Common
> Issue Type: Improvement
> Components: security
> Affects Versions: 2.6.0
> Reporter: Hrishikesh Gadre
> Assignee: Hrishikesh Gadre
> Attachments: hadoop-ldap.patch, multi-scheme-auth-support-poc.patch
>
>
> The requirement is to support LDAP based authentication scheme via Hadoop
> AuthenticationFilter. HADOOP-9054 added a support to plug-in custom
> authentication scheme (in addition to Kerberos) via
> AltKerberosAuthenticationHandler class. But it is based on selecting the
> authentication mechanism based on User-Agent HTTP header which does not
> conform to HTTP protocol semantics.
> As per [RFC-2616|http://www.w3.org/Protocols/rfc2616/rfc2616.html]
> - HTTP protocol provides a simple challenge-response authentication mechanism
> that can be used by a server to challenge a client request and by a client to
> provide the necessary authentication information.
> - This mechanism is initiated by server sending the 401 (Authenticate)
> response with ‘WWW-Authenticate’ header which includes at least one challenge
> that indicates the authentication scheme(s) and parameters applicable to the
> Request-URI.
> - In case server supports multiple authentication schemes, it may return
> multiple challenges with a 401 (Authenticate) response, and each challenge
> may use a different auth-scheme.
> - A user agent MUST choose to use the strongest auth-scheme it understands
> and request credentials from the user based upon that challenge.
> The existing Hadoop authentication filter implementation supports Kerberos
> authentication scheme and uses ‘Negotiate’ as the challenge as part of
> ‘WWW-Authenticate’ response header. As per the following documentation,
> ‘Negotiate’ challenge scheme is only applicable to Kerberos (and Windows
> NTLM) authentication schemes.
> [SPNEGO-based Kerberos and NTLM HTTP
> Authentication|http://tools.ietf.org/html/rfc4559]
> [Understanding HTTP
> Authentication|https://msdn.microsoft.com/en-us/library/ms789031%28v=vs.110%29.aspx]
> On the other hand for LDAP authentication, typically ‘Basic’ authentication
> scheme is used (Note TLS is mandatory with Basic authentication scheme).
> http://httpd.apache.org/docs/trunk/mod/mod_authnz_ldap.html
> Hence for this feature, the idea would be to provide a custom implementation
> of Hadoop AuthenticationHandler and Authenticator interfaces which would
> support both schemes - Kerberos (via Negotiate auth challenge) and LDAP (via
> Basic auth challenge). During the authentication phase, it would send both
> the challenges and let client pick the appropriate one. If client responds
> with an ‘Authorization’ header tagged with ‘Negotiate’ - it will use Kerberos
> authentication. If client responds with an ‘Authorization’ header tagged with
> ‘Basic’ - it will use LDAP authentication.
> Note - some HTTP clients (e.g. curl or Apache Http Java client) need to be
> configured to use one scheme over the other e.g.
> - curl tool supports option to use either Kerberos (via --negotiate flag) or
> username/password based authentication (via --basic and -u flags).
> - Apache HttpClient library can be configured to use specific authentication
> scheme.
> http://hc.apache.org/httpcomponents-client-ga/tutorial/html/authentication.html
> Typically web browsers automatically choose an authentication scheme based on
> a notion of “strength” of security. e.g. take a look at the [design of Chrome
> browser for HTTP
> authentication|https://www.chromium.org/developers/design-documents/http-authentication]
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