bionic (8) dacs_auth_agent.8.gz

Provided by: dacs_1.4.38a-2build1_amd64 bug

NAME

       dacs_auth_agent - DACS delegated authentication service

SYNOPSIS

       dacs_auth_agent [dacsoptions[1]]

DESCRIPTION

       This web service is part of the DACS suite.

       The dacs_auth_agent web service is used to request DACS credentials outside of the usual DACS
       authentication procedure (see dacs_authenticate(8)[2]). The client making the service request, whether a
       user agent or middleware, is considered to be an "agent" trusted by the jurisdiction that receives the
       request by virtue of having obtained DACS credentials and satisfying DACS access control rules that grant
       it access to this service. In other words, an agent simply requests credentials for a given identity from
       dacs_auth_agent and they are returned if an access control rule grants access and dacs_auth_agent is
       configured appropriately.

       The agent's DACS credentials can be obtained through dacs_authenticate(8)[2], dacs_auth_transfer(8)[3],
       dacscred(1)[4], dacscookie(1)[5], or even dacs_auth_agent.

       If the request is successful, credentials are returned to the client within an HTTP cookie. Credentials
       generated by this service can be distinguished from those created by one of the other methods.

           Security
           Access control rules are responsible for expressing restrictions on the types of operations to be
           granted to various trusted agents. Access to this web service must not be granted without
           establishing and testing carefully crafted access control rules and appropriate configuration. By
           default, all access to this service is denied.

       Much like Unix's su(1)[6] command lets the superuser assume the Unix identity of any other user, this
       service provides a way for a privileged client to request credentials for a user known to the receiving
       jurisdiction. Any other credentials in the possession of the client remain in effect. Help desk personnel
       and system administrators can use this capability to assist users by temporarily impersonating a user
       without having to know the user's password, obtaining the user's client certificate, or following the
       user's usual authentication procedure.

       The service can also be invoked to effectively import an identity that is recognized by the agent but
       possibly not known to the receiving jurisdiction. This provides a way to convert foreign credentials,
       whether from a non-DACS based system or a different DACS federation, into credentials understood by the
       federation of the receiving jurisdiction. It is only necessary for the agent to understand the foreign
       credentials; DACS never sees them.

       Another use of this service is in conjunction with middleware that does its own authentication. Having
       authenticated a user, an application can ask dacs_auth_agent for DACS credentials for the user.

   Web Service Arguments
       In addition to the standard CGI arguments[7], dacs_auth_agent understands the following CGI arguments:

       USERNAME
           If present, the agent asserts that USERNAME is in some sense known to this jurisdiction.

       ALIEN_FEDERATION
           If present, the agent asserts that ALIEN_USERNAME, which must be provided, is associated with the
           named external system. This can be any string comprised of characters allowed in a DACS username;
           presumably the agent and DACS jurisdiction have agreed on the name to use. This name, or a string
           mapped from it, will be incorporated into the resulting DACS username and credentials.

       ALIEN_USERNAME
           If present, the ALIEN_FEDERATION argument must also be given. The agent asserts that the given name,
           relative to ALIEN_FEDERATION, has been authenticated. This can be any string comprised of characters
           allowed in a DACS username. This name, or a string mapped from it, will be incorporated into the
           resulting DACS username and credentials.

       DACS_JURISDICTION
           This identifies the receiving jurisdiction.

       DACS_BROWSER
           This optional parameter is as described for the dacs_authenticate(8)[2] service.

       OPERATION
           This optional parameter is as described for the dacs_authenticate(8)[2] service.

       COOKIE_SYNTAX
           This optional parameter is as described for the dacs_authenticate(8)[2] service.

   Operation
       There are two modes of operation. In local mode, the USERNAME argument is provided and is purported to be
       the DACS username of a user known to the receiving jurisdiction.

       The second mode, called alien mode, is selected if both an ALIEN_FEDERATION argument and an
       ALIEN_USERNAME argument are present. It is an error if only one of these arguments is given, and the
       USERNAME is ignored. The mode checks that the ALIEN_FEDERATION and the ALIEN_USERNAME relative to it are
       satisfactory. This is done by requiring the ALIEN_FEDERATION to be recognized by the receiving
       jurisdiction; it may optionally be mapped to a different string. Similarly, the ALIEN_USERNAME argument
       must be recognized, relative to ALIEN_FEDERATION or the string mapped from it.

       Credentials that have been designated as an ADMIN_IDENTITY[8] will be returned only if the
       AUTH_AGENT_ALLOW_ADMIN_IDENTITY[9] configuration directive has the value "yes". Refer to dacs.conf(5)[10]
       for a description of these configuration directives.

       A revocation test is always performed on the DACS identity; see dacs.acls(5)[11] for a description of how
       authentication revocation works.

       Local Mode
           If the USERNAME argument is provided, it must consist of printable characters, as determined by
           isprint(3)[12].

           By default, dacs_auth_agent will blindly accept the trusted client's assertion that USERNAME is known
           to the receiving jurisdiction. An administrator can constrain USERNAME, however, and optionally map
           it into a replacement that is a valid DACS username.

           If the virtual filestore item type "auth_agent_local" is configured, it is expected to name a file
           consisting of expressions, one per line (a continued line ends with a backslash). Each expression is
           evaluated in turn until one returns a non-empty string value; this value, which must be a
           syntactically correct DACS username, becomes the mapped username. An evaluation error is fatal. The
           value of the USERNAME argument is available to each expression as ${Expr::_} (reminiscent of Perl's
           $_ variable).

           For example, consider the configuration directive:

               VFS "[auth_agent_local]dacs-fs:/usr/local/dacs/auth_agent_local_users"

           and the file /usr/local/dacs/auth_agent_local_users, which contains:

               regsub(${Expr::_}, "^auggie doggie$", "auggie")
               regsub(${Expr::_}, "^julia$", "sara")
               strtr(regsub(${Expr::_}, \
                   "\([^:]*\)://\([^.]*\)\\.\(.*\)", '${1}-${2}@${3}'), \
                     "A-Z", "a-z")

           If USERNAME is "auggie doggie", credentials will be issued for "auggie". If USERNAME is "julia",
           credentials will be issued for "sara". If USERNAME is "https://Bob.Example.com", the third expression
           will return the string "https-bob@example.com", which will become the mapped name (this example is
           apropos of mapping OpenID[13] names).

           When configured, roles are obtained for USERNAME in the same way as is done for
           dacs_authenticate(8)[2].

       Alien Mode
           The alien mode of operation proceeds as follows:

            1. It looks up ALIEN_FEDERATION using item type auth_agent_federations. When forming a key, the
               lookup operation will percent-encode any ':' and '%' characters in ALIEN_FEDERATION, so the same
               encoding is required for keys that appear in auth_agent_federations. If it is not found,
               authentication fails. If found, it may optionally have a value; that value will be used within
               the resulting DACS credentials instead of the ALIEN_FEDERATION argument. In any case, the
               resulting value must be valid for a DACS username.

            2. It looks up ALIEN_USERNAME using an item type constructed by prepending the string
               "auth_agent_federation_" to the federation name derived during the previous step. When forming a
               key, the lookup operation will percent-encode any ':' and '%' characters in ALIEN_USERNAME, so
               the same encoding is required for stored keys. If it is not found, authentication fails. If
               found, it may optionally have a value; that value will be used within the resulting DACS
               credentials instead of the ALIEN_USERNAME argument. In any case, the resulting string must be
               valid for a DACS username.

            3. A DACS username will be formed using the federation name and username strings derived in the
               previous steps.

EXAMPLES

       The following is an example of local mode operation. Assume the following configuration directive is in
       effect:

           VFS "[auth_agent_local]dacs-fs:/usr/local/dacs/auth_agent_local_users"

       Also assume that the file /usr/local/dacs/auth_agent_local_users contains the expression:

           regsub(${Expr::_}, \
               "\([^:]*\)://\([^.]*\)\\.\(.*\)", '${1}-${2}@${3}')

       If a request is made with USERNAME equal to "http://Bob.Example.com", new credentials will be issued for
       "http-Bob@Example.com" relative to the current jurisdiction.

       The following is an example of alien mode operation. Assume the following configuration directives are in
       effect:

           VFS "[auth_agent_federations]dacs-kwv-fs:/usr/local/dacs/auth_agent_feds"
           VFS "[auth_agent_federation_mars]dacs-kwv-fs:/usr/local/dacs/auth_agent_fed_mars"

       Also assume that the file /usr/local/dacs/auth_agent_feds consists of the line

           MARS:

       and the file /usr/local/dacs/auth_agent_fed_mars consists of the line

           gazoo:

       If a request is made with ALIEN_FEDERATION equal to "MARS" and ALIEN_USERNAME equal to "gazoo", the
       request will satisfy alien mode's rules of operation with the strings "MARS" and "gazoo" being used to
       form the DACS username relative to the current jurisdiction (DACS_JURISDICTION).

       If instead ALIEN_FEDERATION were "http://example.com" and the file /usr/local/dacs/auth_agent_feds looked
       like:

           http%3A//example.com:example

       then the string "example" would be used with "gazoo" to form the DACS username.

DIAGNOSTICS

       The program exits 0 if everything was fine, 1 if an error occurred.

NOTES

       The word "alien" is used because it sounds cooler than "foreign" and is arguably easier to spell.

       A superficially similar feature called "affiliated DACS federations", which provides single sign-on
       across federation boundaries, is sometimes a more appropriate solution; see dacs_auth_transfer(8)[3].

BUGS

       It should be possible for keys that are matched against USERNAME to be regular expressions and for the
       corresponding replacement values to interpolate matched substrings.

SEE ALSO

       dacs_authenticate(8)[2], dacs_auth_transfer(8)[3], dacs_current_credentials(8)[14], dacs_signout(8)[15],
       dacs.exprs(5)[16], dacscred(1)[4], dacscookie(1)[5].

AUTHOR

       Distributed Systems Software (www.dss.ca[17])

COPYING

       Copyright2003-2014 Distributed Systems Software. See the LICENSE[18] file that accompanies the
       distribution for licensing information.

NOTES

        1. dacsoptions
           http://dacs.dss.ca/man/dacs.1.html#dacsoptions

        2. dacs_authenticate(8)
           http://dacs.dss.ca/man/dacs_authenticate.8.html

        3. dacs_auth_transfer(8)
           http://dacs.dss.ca/man/dacs_auth_transfer.8.html

        4. dacscred(1)
           http://dacs.dss.ca/man/dacscred.1.html

        5. dacscookie(1)
           http://dacs.dss.ca/man/dacscookie.1.html

        6. su(1)
           http://www.freebsd.org/cgi/man.cgi?query=su&apropos=0&sektion=1&manpath=FreeBSD+10.1-RELEASE&format=html

        7. standard CGI arguments
           http://dacs.dss.ca/man/dacs.services.8.html#standard_cgi_args

        8. ADMIN_IDENTITY
           http://dacs.dss.ca/man/dacs.conf.5.html#ADMIN_IDENTITY

        9. AUTH_AGENT_ALLOW_ADMIN_IDENTITY
           http://dacs.dss.ca/man/dacs.conf.5.html#AUTH_AGENT_ALLOW_ADMIN_IDENTITY

       10. dacs.conf(5)
           http://dacs.dss.ca/man/dacs.conf.5.html

       11. dacs.acls(5)
           http://dacs.dss.ca/man/dacs.acls.5.html

       12. isprint(3)
           http://www.freebsd.org/cgi/man.cgi?query=isprint&apropos=0&sektion=3&manpath=FreeBSD+10.1-RELEASE&format=html

       13. OpenID
           http://openid.net/

       14. dacs_current_credentials(8)
           http://dacs.dss.ca/man/dacs_current_credentials.8.html

       15. dacs_signout(8)
           http://dacs.dss.ca/man/dacs_signout.8.html

       16. dacs.exprs(5)
           http://dacs.dss.ca/man/dacs.exprs.5.html

       17. www.dss.ca
           http://www.dss.ca

       18. LICENSE
           http://dacs.dss.ca/man/../misc/LICENSE