4.5. Configuring a request header identity provider
Configure a request-header
identity provider to identify users from request header values, such as X-Remote-User
. It is typically used in combination with an authenticating proxy, which sets the request header value.
4.5.1. About identity providers in OpenShift Container Platform
By default, only a kubeadmin
user exists on your cluster. To specify an identity provider, you must create a custom resource (CR) that describes that identity provider and add it to the cluster.
OpenShift Container Platform user names containing /
, :
, and %
are not supported.
4.5.2. About request header authentication
A request header identity provider identifies users from request header values, such as X-Remote-User
. It is typically used in combination with an authenticating proxy, which sets the request header value. The request header identity provider cannot be combined with other identity providers that use direct password logins, such as HTPasswd, Keystone, LDAP or Basic authentication.
You can also use the request header identity provider for advanced configurations such as the community-supported SAML authentication. Note that this solution is not supported by Red Hat.
For users to authenticate using this identity provider, they must access https://<namespace_route>/oauth/authorize
(and subpaths) via an authenticating proxy. To accomplish this, configure the OAuth server to redirect unauthenticated requests for OAuth tokens to the proxy endpoint that proxies to https://<namespace_route>/oauth/authorize
.
To redirect unauthenticated requests from clients expecting browser-based login flows:
-
Set the
provider.loginURL
parameter to the authenticating proxy URL that will authenticate interactive clients and then proxy the request tohttps://<namespace_route>/oauth/authorize
.
To redirect unauthenticated requests from clients expecting WWW-Authenticate
challenges:
-
Set the
provider.challengeURL
parameter to the authenticating proxy URL that will authenticate clients expectingWWW-Authenticate
challenges and then proxy the request tohttps://<namespace_route>/oauth/authorize
.
The provider.challengeURL
and provider.loginURL
parameters can include the following tokens in the query portion of the URL:
${url}
is replaced with the current URL, escaped to be safe in a query parameter.For example:
https://www.example.com/sso-login?then=${url}
${query}
is replaced with the current query string, unescaped.For example:
https://www.example.com/auth-proxy/oauth/authorize?${query}
As of OpenShift Container Platform 4.1, your proxy must support mutual TLS.
4.5.2.1. SSPI connection support on Microsoft Windows
Using SSPI connection support on Microsoft Windows is a Technology Preview feature. Technology Preview features are not supported with Red Hat production service level agreements (SLAs), might not be functionally complete, and Red Hat does not recommend to use them for production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information on Red Hat Technology Preview features support scope, see https://access.redhat.com/support/offerings/techpreview/.
The OpenShift CLI (oc
) supports the Security Support Provider Interface (SSPI) to allow for SSO flows on Microsft Windows. If you use the request header identity provider with a GSSAPI-enabled proxy to connect an Active Directory server to OpenShift Container Platform, users can automatically authenticate to OpenShift Container Platform by using the oc
command line interface from a domain-joined Microsoft Windows computer.
4.5.3. Creating a config map
Identity providers use OpenShift Container Platform ConfigMap
objects in the openshift-config
namespace to contain the certificate authority bundle. These are primarily used to contain certificate bundles needed by the identity provider.
Procedure
Define an OpenShift Container Platform
ConfigMap
object containing the certificate authority by using the following command. The certificate authority must be stored in theca.crt
key of theConfigMap
object.$ oc create configmap ca-config-map --from-file=ca.crt=/path/to/ca -n openshift-config
4.5.4. Sample request header CR
The following custom resource (CR) shows the parameters and acceptable values for a request header identity provider.
Request header CR
apiVersion: config.openshift.io/v1 kind: OAuth metadata: name: cluster spec: identityProviders: - name: requestheaderidp 1 mappingMethod: claim 2 type: RequestHeader requestHeader: challengeURL: "https://www.example.com/challenging-proxy/oauth/authorize?${query}" 3 loginURL: "https://www.example.com/login-proxy/oauth/authorize?${query}" 4 ca: 5 name: ca-config-map clientCommonNames: 6 - my-auth-proxy headers: 7 - X-Remote-User - SSO-User emailHeaders: 8 - X-Remote-User-Email nameHeaders: 9 - X-Remote-User-Display-Name preferredUsernameHeaders: 10 - X-Remote-User-Login
- 1
- This provider name is prefixed to the user name in the request header to form an identity name.
- 2
- Controls how mappings are established between this provider’s identities and
User
objects. - 3
- Optional: URL to redirect unauthenticated
/oauth/authorize
requests to, that will authenticate browser-based clients and then proxy their request tohttps://<namespace_route>/oauth/authorize
. The URL that proxies tohttps://<namespace_route>/oauth/authorize
must end with/authorize
(with no trailing slash), and also proxy subpaths, in order for OAuth approval flows to work properly.${url}
is replaced with the current URL, escaped to be safe in a query parameter.${query}
is replaced with the current query string. If this attribute is not defined, thenloginURL
must be used. - 4
- Optional: URL to redirect unauthenticated
/oauth/authorize
requests to, that will authenticate clients which expectWWW-Authenticate
challenges, and then proxy them tohttps://<namespace_route>/oauth/authorize
.${url}
is replaced with the current URL, escaped to be safe in a query parameter.${query}
is replaced with the current query string. If this attribute is not defined, thenchallengeURL
must be used. - 5
- Reference to an OpenShift Container Platform
ConfigMap
object containing a PEM-encoded certificate bundle. Used as a trust anchor to validate the TLS certificates presented by the remote server.重要As of OpenShift Container Platform 4.1, the
ca
field is required for this identity provider. This means that your proxy must support mutual TLS. - 6
- Optional: list of common names (
cn
). If set, a valid client certificate with a Common Name (cn
) in the specified list must be presented before the request headers are checked for user names. If empty, any Common Name is allowed. Can only be used in combination withca
. - 7
- Header names to check, in order, for the user identity. The first header containing a value is used as the identity. Required, case-insensitive.
- 8
- Header names to check, in order, for an email address. The first header containing a value is used as the email address. Optional, case-insensitive.
- 9
- Header names to check, in order, for a display name. The first header containing a value is used as the display name. Optional, case-insensitive.
- 10
- Header names to check, in order, for a preferred user name, if different than the immutable identity determined from the headers specified in
headers
. The first header containing a value is used as the preferred user name when provisioning. Optional, case-insensitive.
Additional resources
-
See Identity provider parameters for information on parameters, such as
mappingMethod
, that are common to all identity providers.
4.5.5. Adding an identity provider to your clusters
After you install your cluster, add an identity provider to it so your users can authenticate.
Prerequisites
- Create an OpenShift Container Platform cluster.
- Create the custom resource (CR) for your identity providers.
- You must be logged in as an administrator.
Procedure
Apply the defined CR:
$ oc apply -f </path/to/CR>
注意If a CR does not exist,
oc apply
creates a new CR and might trigger the following warning:Warning: oc apply should be used on resources created by either oc create --save-config or oc apply
. In this case you can safely ignore this warning.Log in to the cluster as a user from your identity provider, entering the password when prompted.
$ oc login -u <username>
Confirm that the user logged in successfully, and display the user name.
$ oc whoami
4.5.6. Example Apache authentication configuration using request header
This example configures an Apache authentication proxy for the OpenShift Container Platform using the request header identity provider.
Custom proxy configuration
Using the mod_auth_gssapi
module is a popular way to configure the Apache authentication proxy using the request header identity provider; however, it is not required. Other proxies can easily be used if the following requirements are met:
-
Block the
X-Remote-User
header from client requests to prevent spoofing. -
Enforce client certificate authentication in the
RequestHeaderIdentityProvider
configuration. -
Require the
X-Csrf-Token
header be set for all authentication requests using the challenge flow. -
Make sure only the
/oauth/authorize
endpoint and its subpaths are proxied; redirects must be rewritten to allow the backend server to send the client to the correct location. -
The URL that proxies to
https://<namespace_route>/oauth/authorize
must end with/authorize
with no trailing slash. For example,https://proxy.example.com/login-proxy/authorize?…
must proxy tohttps://<namespace_route>/oauth/authorize?…
. -
Subpaths of the URL that proxies to
https://<namespace_route>/oauth/authorize
must proxy to subpaths ofhttps://<namespace_route>/oauth/authorize
. For example,https://proxy.example.com/login-proxy/authorize/approve?…
must proxy tohttps://<namespace_route>/oauth/authorize/approve?…
.
The https://<namespace_route>
address is the route to the OAuth server and can be obtained by running oc get route -n openshift-authentication
.
Configuring Apache authentication using request header
This example uses the mod_auth_gssapi
module to configure an Apache authentication proxy using the request header identity provider.
Prerequisites
Obtain the
mod_auth_gssapi
module from the Optional channel. You must have the following packages installed on your local machine:-
httpd
-
mod_ssl
-
mod_session
-
apr-util-openssl
-
mod_auth_gssapi
-
Generate a CA for validating requests that submit the trusted header. Define an OpenShift Container Platform
ConfigMap
object containing the CA. This is done by running:$ oc create configmap ca-config-map --from-file=ca.crt=/path/to/ca -n openshift-config
The CA must be stored in the
ca.crt
key of theConfigMap
object.- Generate a client certificate for the proxy. You can generate this certificate by using any x509 certificate tooling. The client certificate must be signed by the CA you generated for validating requests that submit the trusted header.
- Create the custom resource (CR) for your identity providers.
Procedure
This proxy uses a client certificate to connect to the OAuth server, which is configured to trust the X-Remote-User
header.
-
Create the certificate for the Apache configuration. The certificate that you specify as the
SSLProxyMachineCertificateFile
parameter value is the proxy’s client certificate that is used to authenticate the proxy to the server. It must useTLS Web Client Authentication
as the extended key type. Create the Apache configuration. Use the following template to provide your required settings and values:
重要Carefully review the template and customize its contents to fit your environment.
LoadModule request_module modules/mod_request.so LoadModule auth_gssapi_module modules/mod_auth_gssapi.so # Some Apache configurations might require these modules. # LoadModule auth_form_module modules/mod_auth_form.so # LoadModule session_module modules/mod_session.so # Nothing needs to be served over HTTP. This virtual host simply redirects to # HTTPS. <VirtualHost *:80> DocumentRoot /var/www/html RewriteEngine On RewriteRule ^(.*)$ https://%{HTTP_HOST}$1 [R,L] </VirtualHost> <VirtualHost *:443> # This needs to match the certificates you generated. See the CN and X509v3 # Subject Alternative Name in the output of: # openssl x509 -text -in /etc/pki/tls/certs/localhost.crt ServerName www.example.com DocumentRoot /var/www/html SSLEngine on SSLCertificateFile /etc/pki/tls/certs/localhost.crt SSLCertificateKeyFile /etc/pki/tls/private/localhost.key SSLCACertificateFile /etc/pki/CA/certs/ca.crt SSLProxyEngine on SSLProxyCACertificateFile /etc/pki/CA/certs/ca.crt # It is critical to enforce client certificates. Otherwise, requests can # spoof the X-Remote-User header by accessing the /oauth/authorize endpoint # directly. SSLProxyMachineCertificateFile /etc/pki/tls/certs/authproxy.pem # To use the challenging-proxy, an X-Csrf-Token must be present. RewriteCond %{REQUEST_URI} ^/challenging-proxy RewriteCond %{HTTP:X-Csrf-Token} ^$ [NC] RewriteRule ^.* - [F,L] <Location /challenging-proxy/oauth/authorize> # Insert your backend server name/ip here. ProxyPass https://<namespace_route>/oauth/authorize AuthName "SSO Login" # For Kerberos AuthType GSSAPI Require valid-user RequestHeader set X-Remote-User %{REMOTE_USER}s GssapiCredStore keytab:/etc/httpd/protected/auth-proxy.keytab # Enable the following if you want to allow users to fallback # to password based authentication when they do not have a client # configured to perform kerberos authentication. GssapiBasicAuth On # For ldap: # AuthBasicProvider ldap # AuthLDAPURL "ldap://ldap.example.com:389/ou=People,dc=my-domain,dc=com?uid?sub?(objectClass=*)" </Location> <Location /login-proxy/oauth/authorize> # Insert your backend server name/ip here. ProxyPass https://<namespace_route>/oauth/authorize AuthName "SSO Login" AuthType GSSAPI Require valid-user RequestHeader set X-Remote-User %{REMOTE_USER}s env=REMOTE_USER GssapiCredStore keytab:/etc/httpd/protected/auth-proxy.keytab # Enable the following if you want to allow users to fallback # to password based authentication when they do not have a client # configured to perform kerberos authentication. GssapiBasicAuth On ErrorDocument 401 /login.html </Location> </VirtualHost> RequestHeader unset X-Remote-User
注意The
https://<namespace_route>
address is the route to the OAuth server and can be obtained by runningoc get route -n openshift-authentication
.Update the
identityProviders
stanza in the custom resource (CR):identityProviders: - name: requestheaderidp type: RequestHeader requestHeader: challengeURL: "https://<namespace_route>/challenging-proxy/oauth/authorize?${query}" loginURL: "https://<namespace_route>/login-proxy/oauth/authorize?${query}" ca: name: ca-config-map clientCommonNames: - my-auth-proxy headers: - X-Remote-User
Verify the configuration.
Confirm that you can bypass the proxy by requesting a token by supplying the correct client certificate and header:
# curl -L -k -H "X-Remote-User: joe" \ --cert /etc/pki/tls/certs/authproxy.pem \ https://<namespace_route>/oauth/token/request
Confirm that requests that do not supply the client certificate fail by requesting a token without the certificate:
# curl -L -k -H "X-Remote-User: joe" \ https://<namespace_route>/oauth/token/request
Confirm that the
challengeURL
redirect is active:# curl -k -v -H 'X-Csrf-Token: 1' \ https://<namespace_route>/oauth/authorize?client_id=openshift-challenging-client&response_type=token
Copy the
challengeURL
redirect to use in the next step.Run this command to show a
401
response with aWWW-Authenticate
basic challenge, a negotiate challenge, or both challenges:# curl -k -v -H 'X-Csrf-Token: 1' \ <challengeURL_redirect + query>
Test logging in to the OpenShift CLI (
oc
) with and without using a Kerberos ticket:If you generated a Kerberos ticket by using
kinit
, destroy it:# kdestroy -c cache_name 1
- 1
- Make sure to provide the name of your Kerberos cache.
Log in to the
oc
tool by using your Kerberos credentials:# oc login
Enter your Kerberos user name and password at the prompt.
Log out of the
oc
tool:# oc logout
Use your Kerberos credentials to get a ticket:
# kinit
Enter your Kerberos user name and password at the prompt.
Confirm that you can log in to the
oc
tool:# oc login
If your configuration is correct, you are logged in without entering separate credentials.