Chapter 9. Configuring certificate mapping rules in Identity Management

9.1. Certificate mapping rules for configuring authentication on smart cards

Certificate mapping rules are a convenient way of allowing users to authenticate using certificates in scenarios when the Identity Management (IdM) administrator does not have access to certain users' certificates. This lack of access is typically caused by the fact that the certificates have been issued by an external certificate authority. A special use case is represented by certificates issued by the Certificate System of an Active Directory (AD) with which the IdM domain is in a trust relationship.

Certificate mapping rules are also convenient if the IdM environment is large with a lot of users using smart cards. In this situation, adding full certificates can be complicated. The subject and issuer are predictable in most scenarios and thus easier to add ahead of time than the full certificate. As a system administrator, you can create a certificate mapping rule and add certificate mapping data to a user entry even before a certificate is issued to a particular user. Once the certificate is issued, the user can log in using the certificate even though the full certificate has not yet been uploaded to the user entry.

In addition, as certificates have to be renewed at regular intervals, certificate mapping rules reduce administrative overhead. When a user’s certificate gets renewed, the administrator does not have to update the user entry. For example, if the mapping is based on the Subject and Issuer values, and if the new certificate has the same subject and issuer as the old one, the mapping still applies. If, in contrast, the full certificate was used, then the administrator would have to upload the new certificate to the user entry to replace the old one.

To set up certificate mapping:

  1. An administrator has to load the certificate mapping data (typically the issuer and subject) or the full certificate into a user account.

  2. An administrator has to create a certificate mapping rule to allow successful logging into IdM for a user

    1. whose account contains a certificate mapping data entry
    2. whose certificate mapping data entry matches the information on the certificate

    For details on the individual components that make up a mapping rule and how to obtain and use them, see Components of an identity mapping rule in IdM and Obtaining the issuer from a certificate for use in a matching rule.

Afterwards, when the end-user presents the certificate, stored either in the filesystem or on a smart card, authentication is successful.

9.1.1. Certificate mapping rules for trusts with Active Directory domains

This section outlines the different certificate mapping use cases that are possible if an IdM deployment is in a trust relationship with an Active Directory (AD) domain.

Certificate mapping rules are a convenient way to enable access to IdM resources for users who have smart card certificates that were issued by the trusted AD Certificate System. Depending on the AD configuration, the following scenarios are possible:

9.1.2. Components of an identity mapping rule in IdM

This section describes the components of an identity mapping rule in IdM and how to configure them. Each component has a default value that you can override. You can define the components in either the web UI or the CLI. In the CLI, the identity mapping rule is created using the ipa certmaprule-add command.

Mapping rule

The mapping rule component associates (or maps) a certificate with one or more user accounts. The rule defines an LDAP search filter that associates a certificate with the intended user account.

Certificates issued by different certificate authorities (CAs) might have different properties and might be used in different domains. Therefore, IdM does not apply mapping rules unconditionally, but only to the appropriate certificates. The appropriate certificates are defined using matching rules.

Note that if you leave the mapping rule option empty, the certificates are searched in the userCertificate attribute as a DER encoded binary file.

Define the mapping rule in the CLI using the --maprule option.

Matching rule

The matching rule component selects a certificate to which you want to apply the mapping rule. The default matching rule matches certificates with the digitalSignature key usage and clientAuth extended key usage.

Define the matching rule in the CLI using the --matchrule option.

Domain list

The domain list specifies the identity domains in which you want IdM to search the users when processing identity mapping rules. If you leave the option unspecified, IdM searches the users only in the local domain to which the IdM client belongs.

Define the domain in the CLI using the --domain option.

Priority

When multiple rules are applicable to a certificate, the rule with the highest priority takes precedence. All other rules are ignored.

  • The lower the numerical value, the higher the priority of the identity mapping rule. For example, a rule with a priority 1 has higher priority than a rule with a priority 2.
  • If a rule has no priority value defined, it has the lowest priority.

Define the mapping rule priority in the CLI using the --priority option.

Certificate mapping rule example

To define, using the CLI, a certificate mapping rule called simple_rule that allows authentication for a certificate issued by the Smart Card CA of the EXAMPLE.ORG organisation as long as the Subject on that certificate matches a certmapdata entry in a user account in IdM: 

# ipa certmaprule-add simple_rule --matchrule '<ISSUER>CN=Smart Card CA,O=EXAMPLE.ORG' --maprule '(ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})'

9.1.3. Obtaining the issuer from a certificate for use in a matching rule

This procedure describes how to obtain the issuer information from a certificate so that you can copy and paste it into the matching rule of a certificate mapping rule. To get the issuer format required by a matching rule, use the openssl x509 utility.

Prerequisites

  • You have the user certificate in a .pem or .crt format

Procedure

  1. Obtain the user information from the certificate. Use the openssl x509 certificate display and signing utility with:

    • the -noout option to prevent the output of an encoded version of the request
    • the -issuer option to output the issuer name
    • the -in option to specify the input file name to read the certificate from

    • the -nameopt option with the RFC2253 value to display the output with the most specific relative distinguished name (RDN) first

      If the input file contains an Identity Management certificate, the output of the command shows that the Issuer is defined using the Organisation information: 

      # openssl x509 -noout -issuer -in idm_user.crt -nameopt RFC2253
issuer=CN=Certificate Authority,O=REALM.EXAMPLE.COM

      If the input file contains an Active Directory certificate, the output of the command shows that the Issuer is defined using the Domain Component information: 

      # openssl x509 -noout -issuer -in ad_user.crt -nameopt RFC2253
issuer=CN=AD-WIN2012R2-CA,DC=AD,DC=EXAMPLE,DC=COM

  2. Optionally, to create a new mapping rule in the CLI based on a matching rule which specifies that the certificate issuer must be the extracted AD-WIN2012R2-CA of the ad.example.com domain and the subject on the certificate must match the certmapdata entry in a user account in IdM: 

    # ipa certmaprule-add simple_rule --matchrule '<ISSUER>CN=AD-WIN2012R2-CA,DC=AD,DC=EXAMPLE,DC=COM' --maprule '(ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})'

9.1.4. Additional resources

  • See the sss-certmap(5) man page.

9.2. Configuring certificate mapping for users stored in IdM

This user story describes the steps a system administrator must take to enable certificate mapping in IdM if the user for whom certificate authentication is being configured is stored in IdM. This section describes the following:

  • How to set up a certificate mapping rule so that IdM users with certificates that match the conditions specified in the mapping rule and in their certificate mapping data entries can authenticate to IdM.
  • How to enter certificate mapping data to an IdM user entry so that the user can authenticate using multiple certificates as long as they all contain the values specified in the certificate mapping data entry.

Prerequisites

  • The user has an account in IdM.
  • The administrator has either the whole certificate or the certificate mapping data to add to the user entry.

9.2.1. Adding a certificate mapping rule in the IdM web UI

  1. Log in to the IdM web UI as an administrator.
  2. Navigate to Authentication → Certificate Identity Mapping Rules → Certificate Identity Mapping Rules.

  3. Click Add.

    Figure 9.1. Adding a new certificate mapping rule in the IdM web UI

    Screenshot of the IdM Web UI displaying the "Certificate Identity Mapping Rules" sub-tab from the Authentication tab. The "Add" button at the right of the page is highlighted.
  4. Enter the rule name.

  5. Enter the mapping rule. For example, to make IdM search for the Issuer and Subject entries in any certificate presented to them, and base its decision to authenticate or not on the information found in these two entries of the presented certificate: 

    (ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})

  6. Enter the matching rule. For example, to only allow certificates issued by the Smart Card CA of the EXAMPLE.ORG organization to authenticate users to IdM: 

    <ISSUER>CN=Smart Card CA,O=EXAMPLE.ORG

    Figure 9.2. Entering the details for a certificate mapping rule in the IdM web UI

    Screenshot of the "Add Certificate Identity Mapping Rule" pop-up window with the following fields filled in: Rule name (which is required) - Mapping rule - Matching rule. The Priority field is blank and there is also an Add button next to the Domain name label.
  7. Click Add at the bottom of the dialog box to add the rule and close the box.

  8. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD: 

    # systemctl restart sssd

Now you have a certificate mapping rule set up that compares the type of data specified in the mapping rule that it finds on a smart card certificate with the certificate mapping data in your IdM user entries. Once it finds a match, it authenticates the matching user.

9.2.2. Adding a certificate mapping rule in the IdM CLI

  1. Obtain the administrator’s credentials: 

    # kinit admin

  2. Enter the mapping rule and the matching rule the mapping rule is based on. For example, to make IdM search for the Issuer and Subject entries in any certificate presented, and base its decision to authenticate or not on the information found in these two entries of the presented certificate, recognizing only certificates issued by the Smart Card CA of the EXAMPLE.ORG organization: 

    # ipa certmaprule-add rule_name --matchrule '<ISSUER>CN=Smart Card CA,O=EXAMPLE.ORG' --maprule '(ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})'
-------------------------------------------------------
Added Certificate Identity Mapping Rule "rule_name"
-------------------------------------------------------
  Rule name: rule_name
  Mapping rule: (ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})
  Matching rule: <ISSUER>CN=Smart Card CA,O=EXAMPLE.ORG
  Enabled: TRUE

  3. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD: 

    # systemctl restart sssd

Now you have a certificate mapping rule set up that compares the type of data specified in the mapping rule that it finds on a smart card certificate with the certificate mapping data in your IdM user entries. Once it finds a match, it authenticates the matching user.

9.2.3. Adding certificate mapping data to a user entry in the IdM web UI

  1. Log into the IdM web UI as an administrator.
  2. Navigate to Users → Active users → idm_user.
  3. Find the Certificate mapping data option and click Add.

  4. If you have the certificate of idm_user at your disposal:

    1. In the Command-Line Interface, display the certificate using the cat utility or a text editor: 

      [root@server ~]# cat idm_user_certificate.pem
-----BEGIN CERTIFICATE-----
MIIFFTCCA/2gAwIBAgIBEjANBgkqhkiG9w0BAQsFADA6MRgwFgYDVQQKDA9JRE0u
RVhBTVBMRS5DT00xHjAcBgNVBAMMFUNlcnRpZmljYXRlIEF1dGhvcml0eTAeFw0x
ODA5MDIxODE1MzlaFw0yMDA5MDIxODE1MzlaMCwxGDAWBgNVBAoMD0lETS5FWEFN
[...output truncated...]
    2. Copy the certificate.

    3. In the IdM web UI, click Add next to Certificate and paste the certificate into the window that opens up.

      Figure 9.3. Adding a user’s certificate mapping data: certificate

      Screenshot of a page displaying settings for the user "demouser" with an Identity Settings column on the left with entries such as Job Title - First name - Last name - Full name - Display name. The "Account Settings" column is on the right with entries such as User login - Password - UID - GID. The "Add" button for the "Certificates" entry is highlighted.

      Alternatively, if you do not have the certificate of idm_user at your disposal but know the Issuer and the Subject of the certificate, check the radio button of Issuer and subject and enter the values in the two respective boxes.

      Figure 9.4. Adding a user’s certificate mapping data: issuer and subject

      Screenshot of the "Add Certificate Mapping Data" pop-up window with two radial button options: "Certificate mapping data" and "Issuer and subject." "Issuer and subject" is selected and its two fields (Issuer and Subject) have been filled out.
  5. Click Add.

  6. Optionally, if you have access to the whole certificate in the .pem format, verify that the user and certificate are linked:

    1. Use the sss_cache utility to invalidate the record of idm_user in the SSSD cache and force a reload of the idm_user information: 

      # sss_cache -u idm_user

    2. Run the ipa certmap-match command with the name of the file containing the certificate of the IdM user: 

      # ipa certmap-match idm_user_cert.pem
--------------
1 user matched
--------------
 Domain: IDM.EXAMPLE.COM
 User logins: idm_user
----------------------------
Number of entries returned 1
----------------------------

      The output confirms that now you have certificate mapping data added to idm_user and that a corresponding mapping rule exists. This means that you can use any certificate that matches the defined certificate mapping data to authenticate as idm_user.

9.2.4. Adding certificate mapping data to a user entry in the IdM CLI

  1. Obtain the administrator’s credentials: 

    # kinit admin

  2. If you have the certificate of idm_user at your disposal, add the certificate to the user account using the ipa user-add-cert command: 

    # CERT=`cat idm_user_cert.pem | tail -n +2| head -n -1 | tr -d '\r\n'\`
# ipa user-add-certmapdata idm_user --certificate $CERT

    Alternatively, if you do not have the certificate of idm_user at your disposal but know the Issuer and the Subject of idm_user’s certificate: 

    # ipa user-add-certmapdata idm_user --subject "O=EXAMPLE.ORG,CN=test" --issuer "CN=Smart Card CA,O=EXAMPLE.ORG"
--------------------------------------------
Added certificate mappings to user "idm_user"
--------------------------------------------
  User login: idm_user
  Certificate mapping data: X509:<I>O=EXAMPLE.ORG,CN=Smart Card CA<S>CN=test,O=EXAMPLE.ORG

  3. Optionally, if you have access to the whole certificate in the .pem format, verify that the user and certificate are linked:

    1. Use the sss_cache utility to invalidate the record of idm_user in the SSSD cache and force a reload of the idm_user information: 

      # sss_cache -u idm_user

    2. Run the ipa certmap-match command with the name of the file containing the certificate of the IdM user: 

      # ipa certmap-match idm_user_cert.pem
--------------
1 user matched
--------------
 Domain: IDM.EXAMPLE.COM
 User logins: idm_user
----------------------------
Number of entries returned 1
----------------------------

      The output confirms that now you have certificate mapping data added to idm_user and that a corresponding mapping rule exists. This means that you can use any certificate that matches the defined certificate mapping data to authenticate as idm_user.

/include::modules/identity-management/proc_add-certmapdata-to-user.adoc[leveloffset=+1]

9.3. Configuring certificate mapping for users whose AD user entry contains the whole certificate

This user story describes the steps necessary for enabling certificate mapping in IdM if the IdM deployment is in trust with Active Directory (AD), the user is stored in AD and the user entry in AD contains the whole certificate.

Prerequisites

  • The user does not have an account in IdM.
  • The user has an account in AD which contains a certificate.
  • The IdM administrator has access to data on which the IdM certificate mapping rule can be based.

9.3.1. Adding a certificate mapping rule in the IdM web UI

  1. Log into the IdM web UI as an administrator.
  2. Navigate to Authentication → Certificate Identity Mapping Rules → Certificate Identity Mapping Rules.

  3. Click Add.

    Figure 9.5. Adding a new certificate mapping rule in the IdM web UI

    Screenshot of the IdM Web UI displaying the "Certificate Identity Mapping Rules" sub-page from the Authentication tab. The "Add" button to the right is highlighted.
  4. Enter the rule name.

  5. Enter the mapping rule. To have the whole certificate that is presented to IdM for authentication compared to what is available in AD: 

    (userCertificate;binary={cert!bin})

  6. Enter the matching rule. For example, to only allow certificates issued by the AD-ROOT-CA of the AD.EXAMPLE.COM domain to authenticate: 

    <ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com

    Figure 9.6. Certificate mapping rule for a user with a certificate stored in AD

    Screenshot of the "Add Certificate Identity Mapping Rule" pop-up window with the following fields filled in: Rule name (which is required) - Mapping rule - Matching rule. The Priority field is blank and there is also an "Add" button next to the "Domain name" label.
  7. Click Add.

  8. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD in the CLI:: 

    # systemctl restart sssd

9.3.2. Adding a certificate mapping rule in the IdM CLI

  1. Obtain the administrator’s credentials: 

    # kinit admin

  2. Enter the mapping rule and the matching rule the mapping rule is based on. To have the whole certificate that is presented for authentication compared to what is available in AD, only allowing certificates issued by the AD-ROOT-CA of the AD.EXAMPLE.COM domain to authenticate: 

    # ipa certmaprule-add simpleADrule --matchrule '<ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com' --maprule '(userCertificate;binary={cert!bin})' --domain ad.example.com
-------------------------------------------------------
Added Certificate Identity Mapping Rule "simpleADrule"
-------------------------------------------------------
  Rule name: simpleADrule
  Mapping rule: (userCertificate;binary={cert!bin})
  Matching rule: <ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com
  Domain name: ad.example.com
  Enabled: TRUE

  3. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD: 

    # systemctl restart sssd

9.4. Configuring certificate mapping if AD is configured to map user certificates to user accounts

This user story describes the steps necessary for enabling certificate mapping in IdM if the IdM deployment is in trust with Active Directory (AD), the user is stored in AD and the user entry in AD contains certificate mapping data.

Prerequisites

  • The user does not have an account in IdM.
  • The user has an account in AD which contains the altSecurityIdentities attribute, the AD equivalent of the IdM certmapdata attribute.
  • The IdM administrator has access to data on which the IdM certificate mapping rule can be based.

9.4.1. Adding a certificate mapping rule in the IdM web UI

  1. Log into the IdM web UI as an administrator.
  2. Navigate to Authentication → Certificate Identity Mapping Rules → Certificate Identity Mapping Rules.

  3. Click Add.

    Figure 9.7. Adding a new certificate mapping rule in the IdM web UI

    Screenshot of the IdM Web UI displaying the "Certificate Identity Mapping Rules" sub-tab from the Authentication tab. The "Add" button at the right of the page is highlighted.
  4. Enter the rule name.

  5. Enter the mapping rule. For example, to make AD DC search for the Issuer and Subject entries in any certificate presented, and base its decision to authenticate or not on the information found in these two entries of the presented certificate: 

    (altSecurityIdentities=X509:<I>{issuer_dn!ad_x500}<S>{subject_dn!ad_x500})

  6. Enter the matching rule. For example, to only allow certificates issued by the AD-ROOT-CA of the AD.EXAMPLE.COM domain to authenticate users to IdM: 

    <ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com

  7. Enter the domain: 

    ad.example.com

    Figure 9.8. Certificate mapping rule if AD is configured for mapping

    Screenshot of the "Add Certificate Identity Mapping Rule" pop-up window with the following fields filled in: Rule name (which is required) - Mapping rule - Matching rule. The "Priority" field is blank and there is also an "Add" button next to the "Domain name" label.
  8. Click Add.

  9. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD in the CLI:: 

    # systemctl restart sssd

9.4.2. Adding a certificate mapping rule in the IdM CLI

  1. Obtain the administrator’s credentials: 

    # kinit admin

  2. Enter the mapping rule and the matching rule the mapping rule is based on. For example, to make AD search for the Issuer and Subject entries in any certificate presented, and only allow certificates issued by the AD-ROOT-CA of the AD.EXAMPLE.COM domain: 

    # ipa certmaprule-add ad_configured_for_mapping_rule --matchrule '<ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com' --maprule '(altSecurityIdentities=X509:<I>{issuer_dn!ad_x500}<S>{subject_dn!ad_x500})' --domain=ad.example.com
-------------------------------------------------------
Added Certificate Identity Mapping Rule "ad_configured_for_mapping_rule"
-------------------------------------------------------
  Rule name: ad_configured_for_mapping_rule
  Mapping rule: (altSecurityIdentities=X509:<I>{issuer_dn!ad_x500}<S>{subject_dn!ad_x500})
  Matching rule: <ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com
  Domain name: ad.example.com
  Enabled: TRUE

  3. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD: 

    # systemctl restart sssd

9.4.3. Checking certificate mapping data on the AD side

The altSecurityIdentities attribute is the Active Directory (AD) equivalent of certmapdata user attribute in IdM. When configuring certificate mapping in IdM in the scenario when a trusted AD domain is configured to map user certificates to user accounts, the IdM system administrator needs to check that the altSecurityIdentities attribute is set correctly in the user entries in AD.

To check that AD contains the right information for the user stored in AD, use the ldapsearch command.

  • For example, enter the command below to check with the adserver.ad.example.com server that the following conditions apply:

    • The altSecurityIdentities attribute is set in the user entry of ad_user.

    • The matchrule stipulates that the following conditions apply:

      • The certificate that ad_user uses to authenticate to AD was issued by AD-ROOT-CA of the ad.example.com domain.
      • The subject is <S>DC=com,DC=example,DC=ad,CN=Users,CN=ad_user: 
    $ ldapsearch -o ldif-wrap=no -LLL -h adserver.ad.example.com \
-p 389 -D cn=Administrator,cn=users,dc=ad,dc=example,dc=com \
-W -b cn=users,dc=ad,dc=example,dc=com "(cn=ad_user)" \
altSecurityIdentities
Enter LDAP Password:
dn: CN=ad_user,CN=Users,DC=ad,DC=example,DC=com
altSecurityIdentities: X509:<I>DC=com,DC=example,DC=ad,CN=AD-ROOT-CA<S>DC=com,DC=example,DC=ad,CN=Users,CN=ad_user

9.5. Configuring certificate mapping if AD user entry contains no certificate or mapping data

This user story describes the steps necessary for enabling certificate mapping in IdM if the IdM deployment is in trust with Active Directory (AD), the user is stored in AD and the user entry in AD contains neither the whole certificate nor certificate mapping data.

Prerequisites

  • The user does not have an account in IdM.
  • The user has an account in AD which contains neither the whole certificate nor the altSecurityIdentities attribute, the AD equivalent of the IdM certmapdata attribute.
  • The IdM administrator has the whole AD user certificate to add to the AD user’s user ID override in IdM.

9.5.1. Adding a certificate mapping rule in the IdM web UI

  1. Log into the IdM web UI as an administrator.
  2. Navigate to Authentication → Certificate Identity Mapping Rules → Certificate Identity Mapping Rules.

  3. Click Add.

    Figure 9.9. Adding a new certificate mapping rule in the IdM web UI

    Screenshot of the IdM Web UI displaying the "Certificate Identity Mapping Rules" sub-page from the Authentication tab. The "Add" button to the right is highlighted
  4. Enter the rule name.

  5. Enter the mapping rule. To have the whole certificate that is presented to IdM for authentication compared to the certificate stored in the user ID override entry of the AD user entry in IdM: 

    (userCertificate;binary={cert!bin})

  6. Enter the matching rule. For example, to only allow certificates issued by the AD-ROOT-CA of the AD.EXAMPLE.COM domain to authenticate: 

    <ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com

  7. Enter the domain name. For example, to search for users in the ad.example.com domain:

    Figure 9.10. Certificate mapping rule for a user with no certificate or mapping data stored in AD

    Screenshot of the "Add Certificate Identity Mapping Rule" pop-up window with the following fields filled in: Rule name (which is required) - Mapping rule - Matching rule. The "Priority" field is blank and there is also an Add button next to the "Domain name" label.
  8. Click Add.

  9. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD in the CLI: 

    # systemctl restart sssd

9.5.2. Adding a certificate mapping rule in the IdM CLI

  1. Obtain the administrator’s credentials: 

    # kinit admin

  2. Enter the mapping rule and the matching rule the mapping rule is based on. To have the whole certificate that is presented for authentication compared to the certificate stored in the user ID override entry of the AD user entry in IdM, only allowing certificates issued by the AD-ROOT-CA of the AD.EXAMPLE.COM domain to authenticate: 

    # ipa certmaprule-add simpleADrule --matchrule '<ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com' --maprule '(userCertificate;binary={cert!bin})' --domain ad.example.com
-------------------------------------------------------
Added Certificate Identity Mapping Rule "simpleADrule"
-------------------------------------------------------
  Rule name: simpleADrule
  Mapping rule: (userCertificate;binary={cert!bin})
  Matching rule: <ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com
  Domain name: ad.example.com
  Enabled: TRUE

  3. The System Security Services Daemon (SSSD) periodically re-reads the certificate mapping rules. To force the newly-created rule to be loaded immediately, restart SSSD: 

    # systemctl restart sssd

9.5.3. Adding a certificate to an AD user’s ID override in the IdM web UI

  1. Navigate to Identity → ID Views → Default Trust View.

  2. Click Add.

    Figure 9.11. Adding a new user ID override in the IdM web UI

    Screenshot of the IdM Web UI displaying the "ID Views" page from the Identity tab. The Add button on the right is highlighted.
  3. In the User to override field, enter ad_user@ad.example.com.

  4. Copy and paste the certificate of ad_user into the Certificate field.

    Figure 9.12. Configuring the User ID override for an AD user

    Screenshot displaying the "Add User ID override" pop-up window with the following fields: User to override (which is required) - User login - GECOS - UID - GID - Certificate (which has been filled in with the plaintext version of a certificate).
  5. Click Add.

Verification steps

  • Verify that the user and certificate are linked:

    • Use the sss_cache utility to invalidate the record of ad_user@ad.example.com in the SSSD cache and force a reload of the ad_user@ad.example.com information: 

      # sss_cache -u ad_user@ad.example.com

    • Run the ipa certmap-match command with the name of the file containing the certificate of the AD user: 

      # ipa certmap-match ad_user_cert.pem
--------------
1 user matched
--------------
 Domain: AD.EXAMPLE.COM
 User logins: ad_user@ad.example.com
----------------------------
Number of entries returned 1
----------------------------

The output confirms that you have certificate mapping data added to ad_user@ad.example.com and that a corresponding mapping rule defined in Adding a certificate mapping rule if the AD user entry contains no certificate or mapping data exists. This means that you can use any certificate that matches the defined certificate mapping data to authenticate as ad_user@ad.example.com.

9.5.4. Adding a certificate to an AD user’s ID override in the IdM CLI

Additional resources

  1. Obtain the administrator’s credentials: 

    # kinit admin

  2. Store the certificate blob in a new variable called CERT: 

    # CERT=`cat ad_user_cert.pem | tail -n +2| head -n -1 | tr -d '\r\n'\`

  3. Add the certificate of ad_user@ad.example.com to the user account using the ipa idoverrideuser-add-cert command: 

    # ipa idoverrideuser-add-cert ad_user@ad.example.com --certificate $CERT

Verification steps

  • Verify that the user and certificate are linked:

    • Use the sss_cache utility to invalidate the record of ad_user@ad.example.com in the SSSD cache and force a reload of the ad_user@ad.example.com information: 

      # sss_cache -u ad_user@ad.example.com

    • Run the ipa certmap-match command with the name of the file containing the certificate of the AD user: 

      # ipa certmap-match ad_user_cert.pem
--------------
1 user matched
--------------
 Domain: AD.EXAMPLE.COM
 User logins: ad_user@ad.example.com
----------------------------
Number of entries returned 1
----------------------------

The output confirms that you have certificate mapping data added to ad_user@ad.example.com and that a corresponding mapping rule defined in Adding a certificate mapping rule if the AD user entry contains no certificate or mapping data exists. This means that you can use any certificate that matches the defined certificate mapping data to authenticate as ad_user@ad.example.com.

9.6. Combining several identity mapping rules into one

Additional resources

To combine several identity mapping rules into one combined rule, use the | (or) character to precede the individual mapping rules, and separate them using () brackets, for example:

Certificate mapping filter example 1

$ ipa certmaprule-add ad_cert_for_ipa_and_ad_users \ --maprule='(|(ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})(altSecurityIdentities=X509:<I>{issuer_dn!ad_x500}<S>{subject_dn!ad_x500}))' \ --matchrule='<ISSUER>CN=AD-ROOT-CA,DC=ad,DC=example,DC=com' \ --domain=ad.example.com

In the above example, the filter definition in the --maprule option includes these criteria:

  • ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500} is a filter that links the subject and issuer from a smart card certificate to the value of the ipacertmapdata attribute in an IdM user account, as described in Adding a certificate mapping rule in IdM
  • altSecurityIdentities=X509:<I>{issuer_dn!ad_x500}<S>{subject_dn!ad_x500} is a filter that links the subject and issuer from a smart card certificate to the value of the altSecurityIdentities attribute in an AD user account, as described in Adding a certificate mapping rule if the trusted AD domain is configured to map user certificates
  • The addition of the --domain=ad.example.com option means that users mapped to a given certificate are not only searched in the local idm.example.com domain but also in the ad.example.com domain

The filter definition in the --maprule option accepts the logical operator | (or), so that you can specify multiple criteria. In this case, the rule maps all user accounts that meet at least one of the criteria.

Certificate mapping filter example 2

$ ipa certmaprule-add ipa_cert_for_ad_users \
  --maprule='(|(userCertificate;binary={cert!bin})(ipacertmapdata=X509:<I>{issuer_dn!nss_x500}<S>{subject_dn!nss_x500})(altSecurityIdentities=X509:<I>{issuer_dn!ad_x500}<S>{subject_dn!ad_x500}))' \
  --matchrule='<ISSUER>CN=Certificate Authority,O=REALM.EXAMPLE.COM' \
  --domain=idm.example.com --domain=ad.example.com

In the above example, the filter definition in the --maprule option includes these criteria:

The filter definition in the --maprule option accepts the logical operator | (or), so that you can specify multiple criteria. In this case, the rule maps all user accounts that meet at least one of the criteria.