43 KiB
stage | group | info | type |
---|---|---|---|
Manage | Authentication and Authorization | To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments | reference |
SAML OmniAuth Provider (FREE SELF)
This page describes instance-wide SAML for self-managed GitLab instances. For SAML on GitLab.com, see SAML SSO for GitLab.com groups.
You should also reference the OmniAuth documentation for general settings that apply to all OmniAuth providers.
Glossary of common terms
Term | Description |
---|---|
Identity provider (IdP) | The service which manages your user identities, such as Okta or OneLogin. |
Service provider (SP) | GitLab can be configured as a SAML 2.0 SP. |
Assertion | A piece of information about a user's identity, such as their name or role. Also known as claims or attributes. |
Single Sign-On (SSO) | Name of authentication scheme. |
Assertion consumer service URL | The callback on GitLab where users are redirected after successfully authenticating with the identity provider. |
Issuer | How GitLab identifies itself to the identity provider. Also known as a "Relying party trust identifier". |
Certificate fingerprint | Used to confirm that communications over SAML are secure by checking that the server is signing communications with the correct certificate. Also known as a certificate thumbprint. |
General Setup
GitLab can be configured to act as a SAML 2.0 Service Provider (SP). This allows GitLab to consume assertions from a SAML 2.0 Identity Provider (IdP), such as Okta to authenticate users.
First configure SAML 2.0 support in GitLab, then register the GitLab application in your SAML IdP:
-
Make sure GitLab is configured with HTTPS. See Using HTTPS for instructions.
-
On your GitLab server, open the configuration file.
For Omnibus package:
sudo editor /etc/gitlab/gitlab.rb
For installations from source:
cd /home/git/gitlab sudo -u git -H editor config/gitlab.yml
-
See Configure initial settings for initial settings.
-
To allow your users to use SAML to sign up without having to manually create an account first, add the following values to your configuration:
For Omnibus package:
gitlab_rails['omniauth_allow_single_sign_on'] = ['saml'] gitlab_rails['omniauth_block_auto_created_users'] = false
For installations from source:
omniauth: enabled: true allow_single_sign_on: ["saml"] block_auto_created_users: false
-
You can also automatically link SAML users with existing GitLab users if their email addresses match by adding the following setting:
For Omnibus package:
gitlab_rails['omniauth_auto_link_saml_user'] = true
For installations from source:
auto_link_saml_user: true
-
Ensure that the SAML
NameID
and email address are fixed for each user, as described in the section on Security. Otherwise, your users are able to sign in as other authorized users. -
Add the provider configuration:
For Omnibus package:
gitlab_rails['omniauth_providers'] = [ { name: "saml", label: "Provider name", # optional label for login button, defaults to "Saml" args: { assertion_consumer_service_url: "https://gitlab.example.com/users/auth/saml/callback", idp_cert_fingerprint: "43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8", idp_sso_target_url: "https://login.example.com/idp", issuer: "https://gitlab.example.com", name_identifier_format: "urn:oasis:names:tc:SAML:2.0:nameid-format:persistent" } } ]
For installations from source:
omniauth: providers: - { name: 'saml', label: 'Provider name', # optional label for login button, defaults to "Saml" args: { assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback', idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8', idp_sso_target_url: 'https://login.example.com/idp', issuer: 'https://gitlab.example.com', name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent' } }
-
Change the value for
assertion_consumer_service_url
to match the HTTPS endpoint of GitLab (appendusers/auth/saml/callback
to the HTTPS URL of your GitLab installation to generate the correct value). -
Change the values of
idp_cert_fingerprint
,idp_sso_target_url
,name_identifier_format
to match your IdP. If a fingerprint is used it must be a SHA1 fingerprint; check the OmniAuth SAML documentation for more details on these options. See the notes on configuring your identity provider for more information. -
Change the value of
issuer
to a unique name, which identifies the application to the IdP. -
For the changes to take effect, you must reconfigure GitLab if you installed via Omnibus or restart GitLab if you installed from source.
-
Register the GitLab SP in your SAML 2.0 IdP, using the application name specified in
issuer
.
To ease configuration, most IdP accept a metadata URL for the application to provide
configuration information to the IdP. To build the metadata URL for GitLab, append
users/auth/saml/metadata
to the HTTPS URL of your GitLab installation, for instance:
https://gitlab.example.com/users/auth/saml/metadata
At a minimum the IdP must provide a claim containing the user's email address using email
or mail
.
See the assertions list for other available claims.
On the sign in page there should now be a SAML button below the regular sign in form. Select the icon to begin the authentication process. If everything goes well the user is returned to GitLab and signed in.
Use multiple SAML identity providers
Introduced in GitLab 14.6.
You can configure GitLab to use multiple SAML identity providers if:
- Each provider has a unique name set that matches a name set in
args
. - The providers' names are:
- Used in OmniAuth configuration for properties based on the provider name. For example,
allowBypassTwoFactor
,allowSingleSignOn
, andsyncProfileFromProvider
. - Used for association to each existing user as an additional identity.
- Used in OmniAuth configuration for properties based on the provider name. For example,
- The
assertion_consumer_service_url
matches the provider name. - The
strategy_class
is explicitly set because it cannot be inferred from provider name.
Example multiple providers configuration for Omnibus GitLab:
gitlab_rails['omniauth_providers'] = [
{
name: 'saml_1',
args: {
name: 'saml_1', # This is mandatory and must match the provider name
strategy_class: 'OmniAuth::Strategies::SAML',
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml_1/callback', # URL must match the name of the provider
... # Put here all the required arguments similar to a single provider
},
label: 'Provider 1' # Differentiate the two buttons and providers in the UI
},
{
name: 'saml_2',
args: {
name: 'saml_2', # This is mandatory and must match the provider name
strategy_class: 'OmniAuth::Strategies::SAML',
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml_2/callback', # URL must match the name of the provider
... # Put here all the required arguments similar to a single provider
},
label: 'Provider 2' # Differentiate the two buttons and providers in the UI
}
]
Example providers configuration for installations from source:
omniauth:
providers:
- {
name: 'saml_1',
args: {
name: 'saml_1', # This is mandatory and must match the provider name
strategy_class: 'OmniAuth::Strategies::SAML',
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml_1/callback', # URL must match the name of the provider
... # Put here all the required arguments similar to a single provider
},
label: 'Provider 1' # Differentiate the two buttons and providers in the UI
}
- {
name: 'saml_2',
args: {
name: 'saml_2', # This is mandatory and must match the provider name
strategy_class: 'OmniAuth::Strategies::SAML',
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml_2/callback', # URL must match the name of the provider
... # Put here all the required arguments similar to a single provider
},
label: 'Provider 2' # Differentiate the two buttons and providers in the UI
}
Notes on configuring your identity provider
When configuring a SAML app on the IdP, you need at least:
- Assertion consumer service URL
- Issuer
NameID
- Email address claim
Your identity provider may require additional configuration, such as the following:
Field | Value | Notes |
---|---|---|
SAML profile | Web browser SSO profile | GitLab uses SAML to sign users in through their browser. No requests are made directly to the identity provider. |
SAML request binding | HTTP Redirect | GitLab (the service provider) redirects users to your identity provider with a base64 encoded SAMLRequest HTTP parameter. |
SAML response binding | HTTP POST | Specifies how the SAML token is sent by your identity provider. Includes the SAMLResponse , which a user's browser submits back to GitLab. |
Sign SAML response | Required | Prevents tampering. |
X.509 certificate in response | Required | Signs the response and checks against the provided fingerprint. |
Fingerprint algorithm | SHA-1 | GitLab uses a SHA-1 hash of the certificate to sign the SAML Response. |
Signature algorithm | SHA-1/SHA-256/SHA-384/SHA-512 | Determines how a response is signed. Also known as the digest method, this can be specified in the SAML response. |
Encrypt SAML assertion | Optional | Uses TLS between your identity provider, the user's browser, and GitLab. |
Sign SAML assertion | Optional | Validates the integrity of a SAML assertion. When active, signs the whole response. |
Check SAML request signature | Optional | Checks the signature on the SAML response. |
Default RelayState | Optional | Specifies the URL users should end up on after successfully signing in through SAML at your identity provider. |
NameID format | Persistent | See NameID format details. |
Additional URLs | Optional | May include the issuer (or identifier) or the assertion consumer service URL in other fields on some providers. |
For example configurations, see the notes on specific providers.
Assertions
Field | Supported keys |
---|---|
Email (required) | email , mail |
Full Name | name |
First Name | first_name , firstname , firstName |
Last Name | last_name , lastname , lastName |
See attribute_statements
for examples on how custom
assertions are configured. This section also describes how to configure custom
username attributes.
Please refer to the OmniAuth SAML gem for a full list of supported assertions.
SAML Groups
You can require users to be members of a certain group, or assign users external, administrator or auditor roles based on group membership. These groups are checked on each SAML login and user attributes updated as necessary. This feature does not allow you to automatically add users to GitLab Groups.
Support for these groups depends on your subscription and whether you've installed GitLab Enterprise Edition (EE).
Group | Tier | GitLab Enterprise Edition (EE) Only? |
---|---|---|
Required | (FREE SELF) | Yes |
External | (FREE SELF) | No |
Admin | (FREE SELF) | Yes |
Auditor | (PREMIUM SELF) | Yes |
Requirements
First tell GitLab where to look for group information. For this, you
must make sure that your IdP server sends a specific AttributeStatement
along
with the regular SAML response. Here is an example:
<saml:AttributeStatement>
<saml:Attribute Name="Groups">
<saml:AttributeValue xsi:type="xs:string">Developers</saml:AttributeValue>
<saml:AttributeValue xsi:type="xs:string">Freelancers</saml:AttributeValue>
<saml:AttributeValue xsi:type="xs:string">Admins</saml:AttributeValue>
<saml:AttributeValue xsi:type="xs:string">Auditors</saml:AttributeValue>
</saml:Attribute>
</saml:AttributeStatement>
The name of the attribute can be anything you like, but it must contain the groups
to which a user belongs. To tell GitLab where to find these groups, you need
to add a groups_attribute:
element to your SAML settings.
Required groups
Your IdP passes Group information to the SP (GitLab) in the SAML Response. To use this response, configure GitLab to identify:
- Where to look for the groups in the SAML response via the
groups_attribute
setting - Which group membership is requisite to sign in via the
required_groups
setting
When required_groups
is empty or not set, anyone with proper authentication
is able to use the service.
Example:
{ name: 'saml',
label: 'Our SAML Provider',
groups_attribute: 'Groups',
required_groups: ['Developers', 'Freelancers', 'Admins', 'Auditors'],
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
} }
External groups
SAML login supports the automatic identification of a user as an external user. This is based on the user's group membership in the SAML identity provider.
{ name: 'saml',
label: 'Our SAML Provider',
groups_attribute: 'Groups',
external_groups: ['Freelancers'],
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
} }
Administrator groups
The requirements are the same as the previous settings:
- The IdP must pass Group information to GitLab.
- GitLab must know where to look for the groups in the SAML response, as well as which groups grant the user administrator access.
{ name: 'saml',
label: 'Our SAML Provider',
groups_attribute: 'Groups',
admin_groups: ['Admins'],
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
} }
Auditor groups (PREMIUM SELF)
Introduced in GitLab 11.4.
The requirements are the same as the previous settings:
- The IdP must pass Group information to GitLab.
- GitLab should know where to look for the groups in the SAML response, as well as which groups include users with the Auditor role.
{ name: 'saml',
label: 'Our SAML Provider',
groups_attribute: 'Groups',
auditor_groups: ['Auditors'],
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
} }
Bypass two factor authentication
If you want some SAML authentication methods to count as 2FA on a per session
basis, you can register them in the upstream_two_factor_authn_contexts
list.
In addition to the changes in GitLab, make sure that your IdP is returning the
AuthnContext
. For example:
<saml:AuthnStatement>
<saml:AuthnContext>
<saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:MediumStrongCertificateProtectedTransport</saml:AuthnContextClassRef>
</saml:AuthnContext>
</saml:AuthnStatement>
For Omnibus installations:
-
Edit
/etc/gitlab/gitlab.rb
:gitlab_rails['omniauth_providers'] = [ { name: "saml", args: { assertion_consumer_service_url: "https://gitlab.example.com/users/auth/saml/callback", idp_cert_fingerprint: "43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8", idp_sso_target_url: "https://login.example.com/idp", issuer: "https://gitlab.example.com", name_identifier_format: "urn:oasis:names:tc:SAML:2.0:nameid-format:persistent", upstream_two_factor_authn_contexts: %w( urn:oasis:names:tc:SAML:2.0:ac:classes:CertificateProtectedTransport urn:oasis:names:tc:SAML:2.0:ac:classes:SecondFactorOTPSMS urn:oasis:names:tc:SAML:2.0:ac:classes:SecondFactorIGTOKEN ) }, label: "Company Login" # optional label for SAML login button, defaults to "Saml" } ]
-
Save the file and reconfigure GitLab for the changes to take effect.
For installations from source:
-
Edit
config/gitlab.yml
:omniauth: providers: - { name: 'saml', args: { assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback', idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8', idp_sso_target_url: 'https://login.example.com/idp', issuer: 'https://gitlab.example.com', name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent', upstream_two_factor_authn_contexts: [ 'urn:oasis:names:tc:SAML:2.0:ac:classes:CertificateProtectedTransport', 'urn:oasis:names:tc:SAML:2.0:ac:classes:SecondFactorOTPSMS', 'urn:oasis:names:tc:SAML:2.0:ac:classes:SecondFactorIGTOKEN' ] }, label: 'Company Login' # optional label for SAML login button, defaults to "Saml" }
-
Save the file and restart GitLab for the changes to take effect
Customization
auto_sign_in_with_provider
You can add this setting to your GitLab configuration to automatically redirect you to your SAML server for authentication. This removes the requirement to select a button before actually signing in.
For Omnibus package:
gitlab_rails['omniauth_auto_sign_in_with_provider'] = 'saml'
For installations from source:
omniauth:
auto_sign_in_with_provider: saml
Keep in mind that every sign in attempt redirects to the SAML server; you cannot sign in using local credentials. Ensure at least one of the SAML users has administrator access.
You may also bypass the auto sign-in feature by browsing to
https://gitlab.example.com/users/sign_in?auto_sign_in=false
.
attribute_statements
(FREE SELF)
NOTE:
This setting should be used only to map attributes that are part of the OmniAuth
info
hash schema.
attribute_statements
is used to map Attribute Names in a SAMLResponse to entries
in the OmniAuth info
hash.
For example, if your SAMLResponse contains an Attribute called EmailAddress
,
specify { email: ['EmailAddress'] }
to map the Attribute to the
corresponding key in the info
hash. URI-named Attributes are also supported, for example,
{ email: ['http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress'] }
.
This setting allows you tell GitLab where to look for certain attributes required
to create an account. Like mentioned above, if your IdP sends the user's email
address as EmailAddress
instead of email
, let GitLab know by setting it on
your configuration:
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
attribute_statements: { email: ['EmailAddress'] }
}
Set a username
By default, the local part of the email address in the SAML response is used to generate the user's GitLab username.
Configure nickname
in attribute_statements
to specify one or more attributes that contain a user's desired username:
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
attribute_statements: { nickname: ['username'] }
}
This also sets the username
attribute in your SAML Response to the username in GitLab.
allowed_clock_drift
The clock of the Identity Provider may drift slightly ahead of your system clocks.
To allow for a small amount of clock drift, you can use allowed_clock_drift
in
your settings. Its value must be given in a number (and/or fraction) of seconds.
The value given is added to the current time at which the response is validated.
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
attribute_statements: { email: ['EmailAddress'] },
allowed_clock_drift: 1 # for one second clock drift
}
uid_attribute
By default, the uid
is set as the name_id
in the SAML response. If you'd like to designate a unique attribute for the uid
, you can set the uid_attribute
. In the example below, the value of uid
attribute in the SAML response is set as the uid_attribute
.
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
uid_attribute: 'uid'
}
Make sure you read the Security section before changing this value.
Response signature validation (required)
We require Identity Providers to sign SAML responses to ensure that the assertions are not tampered with.
This prevents user impersonation and prevents privilege escalation when specific group membership is required. Typically this:
- Is configured using
idp_cert_fingerprint
. - Includes the full certificate in the response, although if your Identity Provider
doesn't support this, you can directly configure GitLab using the
idp_cert
option.
Example configuration with idp_cert_fingerprint
:
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
}
Example configuration with idp_cert
:
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert: '-----BEGIN CERTIFICATE-----
<redacted>
-----END CERTIFICATE-----',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
}
If the response signature validation is configured incorrectly, you can see error messages such as:
- A key validation error.
- Digest mismatch.
- Fingerprint mismatch.
Refer to the troubleshooting section for more information on debugging these errors.
Assertion Encryption (optional)
GitLab requires the use of TLS encryption with SAML, but in some cases there can be a need for additional encryption of the assertions.
This may be the case, for example, if you terminate TLS encryption early at a load balancer and include sensitive details in assertions that you do not want appearing in logs. Most organizations should not need additional encryption at this layer.
The SAML integration supports EncryptedAssertion. You should define the private key and the public certificate of your GitLab instance in the SAML settings:
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
certificate: '-----BEGIN CERTIFICATE-----
<redacted>
-----END CERTIFICATE-----',
private_key: '-----BEGIN PRIVATE KEY-----
<redacted>
-----END PRIVATE KEY-----'
}
Your Identity Provider encrypts the assertion with the public certificate of GitLab. GitLab decrypts the EncryptedAssertion with its private key.
NOTE:
This integration uses the certificate
and private_key
settings for both assertion encryption and request signing.
Request signing (optional)
Another optional configuration is to sign SAML authentication requests. GitLab SAML Requests use the SAML redirect binding, so this isn't necessary (unlike the SAML POST binding, where signing is required to prevent intermediaries from tampering with the requests).
To sign, create a private key and public certificate pair for your
GitLab instance to use for SAML. The settings for signing can be set in the
security
section of the configuration.
For example:
args: {
assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
idp_cert_fingerprint: '43:51:43:a1:b5:fc:8b:b7:0a:3a:a9:b1:0f:66:73:a8',
idp_sso_target_url: 'https://login.example.com/idp',
issuer: 'https://gitlab.example.com',
name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
certificate: '-----BEGIN CERTIFICATE-----
<redacted>
-----END CERTIFICATE-----',
private_key: '-----BEGIN PRIVATE KEY-----
<redacted>
-----END PRIVATE KEY-----',
security: {
authn_requests_signed: true, # enable signature on AuthNRequest
want_assertions_signed: true, # enable the requirement of signed assertion
embed_sign: true, # embedded signature or HTTP GET parameter signature
metadata_signed: false, # enable signature on Metadata
signature_method: 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256',
digest_method: 'http://www.w3.org/2001/04/xmlenc#sha256',
}
}
GitLab signs the request with the provided private key. GitLab includes the configured public x500 certificate in the metadata for your Identity Provider to validate the signature of the received request with. For more information on this option, see the Ruby SAML gem documentation. The Ruby SAML gem is used by the OmniAuth SAML gem to implement the client side of the SAML authentication.
Security
Avoid user control of the following attributes:
NameID
Email
when used withomniauth_auto_link_saml_user
These attributes define the SAML user. If users can change these attributes, they can impersonate others.
Refer to the documentation for your SAML Identity Provider for information on how to fix these attributes.
Passwords for users created via SAML
The Generated passwords for users created through integrated authentication guide provides an overview of how GitLab generates and sets passwords for users created via SAML.
Link SAML identity for an existing user
A user can manually link their SAML identity to an existing GitLab account by following the steps in Enable OmniAuth for an existing user.
Configuring Group SAML on a self-managed GitLab instance (PREMIUM SELF)
For information on the GitLab.com implementation, please see the SAML SSO for GitLab.com groups page.
Group SAML SSO helps if you have to allow access via multiple SAML identity providers, but as a multi-tenant solution is less suited to cases where you administer your own GitLab instance.
To proceed with configuring Group SAML SSO instead, enable the group_saml
OmniAuth provider. This can be done from:
gitlab.rb
for Omnibus GitLab installations.gitlab/config/gitlab.yml
for source installations.
Limitations
Group SAML on a self-managed instance is limited when compared to the recommended instance-wide SAML. The recommended solution allows you to take advantage of:
Omnibus installations
-
Make sure GitLab is configured with HTTPS.
-
Enable OmniAuth and the
group_saml
provider ingitlab.rb
:gitlab_rails['omniauth_enabled'] = true gitlab_rails['omniauth_providers'] = [{ name: 'group_saml' }]
Source installations
-
Make sure GitLab is configured with HTTPS.
-
Enable OmniAuth and the
group_saml
provider ingitlab/config/gitlab.yml
:omniauth: enabled: true providers: - { name: 'group_saml' }
Providers
GitLab support of SAML means that you can sign in to GitLab with a wide range of identity providers. Your identity provider may have additional documentation. Some identity providers include documentation on how to use SAML to sign in to GitLab.
Examples:
GitLab provides the following setup notes for guidance only. If you have any questions on configuring the SAML app, please contact your provider's support.
Okta setup notes
The following guidance is based on this Okta article, on adding a SAML Application with an Okta Developer account:
- In the Okta administrator section, make sure to select Classic UI view in the top left corner. From there, choose to Add an App.
- When the app screen comes up you see another button to Create an App and choose SAML 2.0 on the next screen.
- Optionally, you can add a logo (you can choose it from https://about.gitlab.com/press/). You must crop and resize it.
- Next, fill in the SAML general configuration with the assertion consumer service URL as "Single sign-on URL" and the issuer as "Audience URI" along with the NameID and assertions.
- The last part of the configuration is the feedback section where you can just say you're a customer and creating an app for internal use.
- When you have your app you can see a few tabs on the top of the app's profile. Select the SAML 2.0 configuration instructions button.
- On the screen that comes up take note of the
Identity Provider Single Sign-On URL which you can use for the
idp_sso_target_url
on your GitLab configuration file. - Before you leave Okta, make sure you add your user and groups if any.
Google workspace setup notes
The following guidance is based on this Google Workspace article, on how to Set up your own custom SAML application:
Make sure you have access to a Google Workspace Super Admin account. Use the information below and follow the instructions in the linked Google Workspace article.
Typical value | Description | |
---|---|---|
Name of SAML App | GitLab | Other names OK. |
ACS URL | https://<GITLAB_DOMAIN>/users/auth/saml/callback |
ACS is short for Assertion Consumer Service. |
GITLAB_DOMAIN | gitlab.example.com |
Set to the domain of your GitLab instance. |
Entity ID | https://gitlab.example.com |
A value unique to your SAML app, set it to the issuer in your GitLab configuration. |
Name ID format | Required value. Also known as name_identifier_format |
|
Name ID | Primary email address | Make sure someone receives content sent to that address |
First name | first_name |
Required value to communicate with GitLab. |
Last name | last_name |
Required value to communicate with GitLab. |
You also must setup the following SAML attribute mappings:
Google Directory attributes | App attributes |
---|---|
Basic information > Email | email |
Basic Information > First name | first_name |
Basic Information > Last name | last_name |
You may also use some of this information when you configure GitLab.
When configuring the Google Workspace SAML app, be sure to record the following information:
Value | Description | |
---|---|---|
SSO URL | Depends | Google Identity Provider details. Set to the GitLab idp_sso_target_url setting. |
Certificate | Downloadable | Run openssl x509 -in <your_certificate.crt> -noout -fingerprint to generate the SHA1 fingerprint that can be used in the idp_cert_fingerprint setting. |
While the Google Workspace Administrator provides IdP metadata, Entity ID, and SHA-256 fingerprint, they are not required. GitLab does not need that information to connect to the Google Workspace SAML app.
Troubleshooting
SAML Response
You can find the base64-encoded SAML Response in the production_json.log
. This response is sent from the IdP, and contains user information that is consumed by GitLab. Many errors in the SAML integration can be solved by decoding this response and comparing it to the SAML settings in the GitLab configuration file.
GitLab+SAML Testing Environments
To troubleshoot, a complete GitLab+SAML testing environment using Docker compose is available.
If you only require a SAML provider for testing, a quick start guide to start a Docker container with a plug and play SAML 2.0 Identity Provider (IdP) is available.
500 error after login
If you see a "500 error" in GitLab when you are redirected back from the SAML sign-in page, this could indicate that:
- GitLab couldn't get the email address for the SAML user. Ensure the IdP provides a claim containing the user's
email address using the claim name
email
ormail
. - The certificate set your
gitlab.rb
file foridp_cert_fingerprint
oridp_cert
file is incorrect. - Your
gitlab.rb
file is set to enableidp_cert_fingerprint
, andidp_cert
is being provided, or the reverse.
422 error after login
If you see a "422 error" in GitLab when you are redirected from the SAML sign-in page, you might have an incorrectly configured Assertion Consumer Service (ACS) URL on the identity provider.
Make sure the ACS URL points to https://gitlab.example.com/users/auth/saml/callback
, where
gitlab.example.com
is the URL of your GitLab instance.
If the ACS URL is correct, and you still have errors, review the other Troubleshooting sections.
If you are sure that the ACS URL is correct, proceed to the Redirect back to the login screen with no evident error section for further troubleshooting steps.
Redirect back to the login screen with no evident error
If after signing in into your SAML server you are redirected back to the sign in page and
no error is displayed, check your production.log
file. It most likely contains the
message Can't verify CSRF token authenticity
. This means that there is an error during
the SAML request, but in GitLab 11.7 and earlier this error never reaches GitLab due to
the CSRF check.
To bypass this you can add skip_before_action :verify_authenticity_token
to the
omniauth_callbacks_controller.rb
file immediately after the class
line and
comment out the protect_from_forgery
line using a #
. Restart Puma for this
change to take effect. This allows the error to hit GitLab, where it can then
be seen in the usual logs, or as a flash message on the login screen.
That file is located in /opt/gitlab/embedded/service/gitlab-rails/app/controllers
for Omnibus installations and by default in /home/git/gitlab/app/controllers
for
installations from source. Restart Puma using the sudo gitlab-ctl restart puma
command on Omnibus installations and sudo service gitlab restart
on installations
from source.
You may also find the SAML Tracer (Firefox) and SAML Chrome Panel (Chrome) browser extensions useful in your debugging.
Invalid audience
This error means that the IdP doesn't recognize GitLab as a valid sender and receiver of SAML requests. Make sure to:
- Add the GitLab callback URL to the approved audiences of the IdP server.
- Avoid trailing whitespace in the
issuer
string.
Missing claims, or Email can't be blank
errors
The IdP server needs to pass certain information in order for GitLab to either
create an account, or match the login information to an existing account. email
is the minimum amount of information that needs to be passed. If the IdP server
is not providing this information, all SAML requests fail.
Make sure this information is provided.
Another issue that can result in this error is when the correct information is being sent by
the IdP, but the attributes don't match the names in the OmniAuth info
hash. In this case,
you must set attribute_statements
in the SAML configuration to map the attribute names in
your SAML Response to the corresponding OmniAuth info
hash names.
Key validation error, Digest mismatch or Fingerprint mismatch
These errors all come from a similar place, the SAML certificate. SAML requests must be validated using either a fingerprint, a certificate, or a validator.
For this requirement, be sure to take the following into account:
- If a fingerprint is used, it must be the SHA1 fingerprint
- If no certificate is provided in the settings, a fingerprint or fingerprint
validator needs to be provided and the response from the server must contain
a certificate (
<ds:KeyInfo><ds:X509Data><ds:X509Certificate>
) - If a certificate is provided in the settings, it is no longer necessary for the request to contain one. In this case the fingerprint or fingerprint validators are optional
If none of the above described scenarios is valid, the request fails with one of the mentioned errors.
User is blocked when signing in through SAML
The following are the most likely reasons that a user is blocked when signing in through SAML:
- In the configuration,
gitlab_rails['omniauth_block_auto_created_users'] = true
is set and this is the user's first time signing in. - There are
required_groups
configured, but the user is not a member of one.
Google workspace troubleshooting tips
The Google Workspace documentation on SAML app error messages is helpful for debugging if you are seeing an error from Google while signing in. Pay particular attention to the following 403 errors:
app_not_configured
app_not_configured_for_user