*: validate InResponseTo SAML response field and make issuer optional
This commit is contained in:
Eric Chiang
parent
95d237003a
commit
50b223a9db
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@ -93,3 +93,46 @@ objectClass: groupOfNames
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member: cn=Test1,dc=example,dc=org
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cn: tstgrp
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```
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## SAML
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### Okta
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The Okta identity provider supports free accounts for developers to test their implementation against. This document describes configuring an Okta application to test dex's SAML connector.
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First, [sign up for a developer account][okta-sign-up]. Then, to create a SAML application:
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* Go to the admin screen.
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* Click "Add application"
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* Click "Create New App"
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* Choose "SAML 2.0" and press "Create"
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* Configure SAML
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* Enter `http://127.0.0.1:5556/dex/callback` for "Single sign on URL"
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* Enter `http://127.0.0.1:5556/dex/callback` for "Audience URI (SP Entity ID)"
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* Under "ATTRIBUTE STATEMENTS (OPTIONAL)" add an "email" and "name" attribute. The values should be something like `user:email` and `user:firstName`, respectively.
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* Under "GROUP ATTRIBUTE STATEMENTS (OPTIONAL)" add a "groups" attribute. Use the "Regexp" filter `.*`.
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After the application's created, assign yourself to the app.
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* "Applications" > "Applications"
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* Click on your application then under the "People" tab press the "Assign to People" button and add yourself.
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At the app, go to the "Sign On" tab and then click "View Setup Instructions". Use those values to fill out the following connector in `examples/config-dev.yaml`.
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```yaml
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connectors:
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- type: samlExperimental
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id: saml
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name: Okta
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config:
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ssoURL: ( "Identity Provider Single Sign-On URL" )
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caData: ( base64'd value of "X.509 Certificate" )
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redirectURI: http://127.0.0.1:5556/dex/callback
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usernameAttr: name
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emailAttr: email
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groupsAttr: groups
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```
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Start both dex and the example app, and try logging in (requires not requesting a refresh token).
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[okta-sign-up]: https://www.okta.com/developer/signup/
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@ -24,8 +24,6 @@ connectors:
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# Required field for connector name.
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name: SAML
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config:
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# Issuer used for validating the SAML response.
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issuer: https://saml.example.com
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# SSO URL used for POST value.
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ssoURL: https://saml.example.com/sso
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@ -72,4 +70,8 @@ connectors:
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# urn:oasis:names:tc:SAML:2.0:nameid-format:persistent
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#
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nameIDPolicyFormat: persistent
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# Optional issuer used for validating the SAML response. If provided the
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# connector will validate the Issuer in the response.
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# issuer: https://saml.example.com
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```
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@ -66,20 +66,25 @@ type CallbackConnector interface {
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}
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// SAMLConnector represents SAML connectors which implement the HTTP POST binding.
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// RelayState is handled by the server.
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//
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// RelayState is handled by the server.
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// See: https://docs.oasis-open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf
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// "3.5 HTTP POST Binding"
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type SAMLConnector interface {
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// POSTData returns an encoded SAML request and SSO URL for the server to
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// render a POST form with.
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POSTData(s Scopes) (sooURL, samlRequest string, err error)
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//
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// POSTData should encode the provided request ID in the returned serialized
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// SAML request.
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POSTData(s Scopes, requestID string) (sooURL, samlRequest string, err error)
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// TODO(ericchiang): Provide expected "InResponseTo" ID value.
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// HandlePOST decodes, verifies, and maps attributes from the SAML response.
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// It passes the expected value of the "InResponseTo" response field, which
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// the connector must ensure matches the response value.
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//
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// See: https://www.oasis-open.org/committees/download.php/35711/sstc-saml-core-errata-2.0-wd-06-diff.pdf
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// "3.2.2 Complex Type StatusResponseType"
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// HandlePOST decodes, verifies, and maps attributes from the SAML response.
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HandlePOST(s Scopes, samlResponse string) (identity Identity, err error)
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HandlePOST(s Scopes, samlResponse, inResponseTo string) (identity Identity, err error)
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}
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// RefreshConnector is a connector that can update the client claims.
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@ -135,7 +135,6 @@ func (c *Config) openConnector(logger logrus.FieldLogger) (interface {
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requiredFields := []struct {
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name, val string
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}{
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{"issuer", c.Issuer},
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{"ssoURL", c.SSOURL},
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{"usernameAttr", c.UsernameAttr},
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{"emailAttr", c.EmailAttr},
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@ -240,7 +239,7 @@ type provider struct {
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logger logrus.FieldLogger
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}
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func (p *provider) POSTData(s connector.Scopes) (action, value string, err error) {
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func (p *provider) POSTData(s connector.Scopes, id string) (action, value string, err error) {
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// NOTE(ericchiang): If we can't follow up with the identity provider, can we
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// support refresh tokens?
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@ -250,28 +249,32 @@ func (p *provider) POSTData(s connector.Scopes) (action, value string, err error
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r := &authnRequest{
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ProtocolBinding: bindingPOST,
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ID: "_" + uuidv4(),
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ID: id,
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IssueInstant: xmlTime(p.now()),
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Destination: p.ssoURL,
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Issuer: &issuer{
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Issuer: p.issuer,
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},
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NameIDPolicy: &nameIDPolicy{
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AllowCreate: true,
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Format: p.nameIDPolicyFormat,
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},
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AssertionConsumerServiceURL: p.redirectURI,
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}
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if p.issuer != "" {
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// Issuer for the request is optional. For example, okta always ignores
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// this value.
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r.Issuer = &issuer{Issuer: p.issuer}
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}
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data, err := xml.MarshalIndent(r, "", " ")
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if err != nil {
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return "", "", fmt.Errorf("marshal authn request: %v", err)
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}
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// See: https://docs.oasis-open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf
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// "3.5.4 Message Encoding"
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return p.ssoURL, base64.StdEncoding.EncodeToString(data), nil
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}
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func (p *provider) HandlePOST(s connector.Scopes, samlResponse string) (ident connector.Identity, err error) {
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func (p *provider) HandlePOST(s connector.Scopes, samlResponse, inResponseTo string) (ident connector.Identity, err error) {
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rawResp, err := base64.StdEncoding.DecodeString(samlResponse)
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if err != nil {
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return ident, fmt.Errorf("decode response: %v", err)
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@ -287,6 +290,17 @@ func (p *provider) HandlePOST(s connector.Scopes, samlResponse string) (ident co
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return ident, fmt.Errorf("unmarshal response: %v", err)
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}
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if p.issuer != "" && resp.Issuer != nil && resp.Issuer.Issuer != p.issuer {
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return ident, fmt.Errorf("expected Issuer value %s, got %s", p.issuer, resp.Issuer.Issuer)
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}
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// Verify InResponseTo value matches the expected ID associated with
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// the RelayState.
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if resp.InResponseTo != inResponseTo {
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return ident, fmt.Errorf("expected InResponseTo value %s, got %s", inResponseTo, resp.InResponseTo)
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}
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// Destination is optional.
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if resp.Destination != "" && resp.Destination != p.redirectURI {
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return ident, fmt.Errorf("expected destination %q got %q", p.redirectURI, resp.Destination)
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@ -327,26 +341,26 @@ func (p *provider) HandlePOST(s connector.Scopes, samlResponse string) (ident co
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}
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if ident.Email, _ = attributes.get(p.emailAttr); ident.Email == "" {
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return ident, fmt.Errorf("no attribute with name %q", p.emailAttr)
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return ident, fmt.Errorf("no attribute with name %q: %s", p.emailAttr, attributes.names())
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}
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ident.EmailVerified = true
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if ident.Username, _ = attributes.get(p.usernameAttr); ident.Username == "" {
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return ident, fmt.Errorf("no attribute with name %q", p.usernameAttr)
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return ident, fmt.Errorf("no attribute with name %q: %s", p.usernameAttr, attributes.names())
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}
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if s.Groups && p.groupsAttr != "" {
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if p.groupsDelim != "" {
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groupsStr, ok := attributes.get(p.groupsAttr)
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if !ok {
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return ident, fmt.Errorf("no attribute with name %q", p.groupsAttr)
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return ident, fmt.Errorf("no attribute with name %q: %s", p.groupsAttr, attributes.names())
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}
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// TODO(ericchiang): Do we need to further trim whitespace?
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ident.Groups = strings.Split(groupsStr, p.groupsDelim)
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} else {
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groups, ok := attributes.all(p.groupsAttr)
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if !ok {
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return ident, fmt.Errorf("no attribute with name %q", p.groupsAttr)
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return ident, fmt.Errorf("no attribute with name %q: %s", p.groupsAttr, attributes.names())
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}
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ident.Groups = groups
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}
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@ -427,6 +441,9 @@ func (p *provider) validateSubjectConfirmation(subject *subject) error {
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}
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// Validates the Conditions element and all of it's content
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//
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// See: https://docs.oasis-open.org/security/saml/v2.0/saml-core-2.0-os.pdf
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// "2.3.3 Element <Assertion>"
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func (p *provider) validateConditions(assertion *assertion) error {
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// Checks if a Conditions element exists
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conditions := assertion.Conditions
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@ -452,15 +469,17 @@ func (p *provider) validateConditions(assertion *assertion) error {
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if audienceRestriction != nil {
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audiences := audienceRestriction.Audiences
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if audiences != nil && len(audiences) > 0 {
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values := make([]string, len(audiences))
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issuerInAudiences := false
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for _, audience := range audiences {
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if audience.Value == p.issuer {
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for i, audience := range audiences {
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if audience.Value == p.redirectURI {
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issuerInAudiences = true
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break
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}
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values[i] = audience.Value
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}
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if !issuerInAudiences {
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return fmt.Errorf("required audience %s was not in Response audiences %s", p.issuer, audiences)
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return fmt.Errorf("required audience %s was not in Response audiences %s", p.redirectURI, values)
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}
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}
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}
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@ -18,8 +18,11 @@ import (
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)
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const (
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defaultIssuer = "http://localhost:5556/dex/callback"
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defaultIssuer = "http://www.okta.com/exk91cb99lKkKSYoy0h7"
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defaultRedirectURI = "http://localhost:5556/dex/callback"
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// Response ID embedded in our testdata.
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testDataResponseID = "_fd1b3ef9-ec09-44a7-a66b-0d39c250f6a0"
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)
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func loadCert(ca string) (*x509.Certificate, error) {
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@ -109,7 +112,7 @@ func TestHandlePOST(t *testing.T) {
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if err != nil {
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t.Fatal(err)
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}
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ident, err := p.HandlePOST(scopes, base64.StdEncoding.EncodeToString(data))
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ident, err := p.HandlePOST(scopes, base64.StdEncoding.EncodeToString(data), testDataResponseID)
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if err != nil {
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t.Fatal(err)
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}
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@ -254,12 +257,12 @@ func TestValidateConditions(t *testing.T) {
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if err != nil {
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t.Fatalf("validation of %q should succeed", "Conditions where notBefore is 15 seconds after now")
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}
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// Audiences contains the issuer
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validAudience := audience{Value: p.issuer}
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// Audiences contains the redirectURI
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validAudience := audience{Value: p.redirectURI}
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cond.AudienceRestriction.Audiences = []audience{validAudience}
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err = p.validateConditions(assert)
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if err != nil {
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t.Fatalf("validation of %q should succeed", "Audiences contains the issuer")
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t.Fatalf("validation of %q should succeed: %v", "Audiences contains the redirectURI", err)
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}
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// Audiences is not empty and not contains the issuer
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invalidAudience := audience{Value: "invalid"}
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@ -162,8 +162,9 @@ type authnContextClassRef struct {
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type response struct {
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XMLName xml.Name `xml:"urn:oasis:names:tc:SAML:2.0:protocol Response"`
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ID string `xml:"ID,attr"`
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Version samlVersion `xml:"Version,attr"`
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ID string `xml:"ID,attr"`
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InResponseTo string `xml:"InResponseTo,attr"`
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Version samlVersion `xml:"Version,attr"`
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Destination string `xml:"Destination,attr,omitempty"`
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@ -221,6 +222,16 @@ func (a *attributeStatement) all(name string) (s []string, ok bool) {
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return
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}
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// names list the names of all attributes in the attribute statement.
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func (a *attributeStatement) names() []string {
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s := make([]string, len(a.Attributes))
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for i, attr := range a.Attributes {
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s[i] = attr.Name
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}
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return s
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}
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type attribute struct {
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XMLName xml.Name `xml:"urn:oasis:names:tc:SAML:2.0:assertion Attribute"`
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@ -247,7 +247,7 @@ func (s *Server) handleConnectorLogin(w http.ResponseWriter, r *http.Request) {
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s.logger.Errorf("Server template error: %v", err)
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}
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case connector.SAMLConnector:
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action, value, err := conn.POSTData(scopes)
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action, value, err := conn.POSTData(scopes, authReqID)
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if err != nil {
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s.logger.Errorf("Creating SAML data: %v", err)
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s.renderError(w, http.StatusInternalServerError, "Connector Login Error")
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@ -360,7 +360,7 @@ func (s *Server) handleConnectorCallback(w http.ResponseWriter, r *http.Request)
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s.renderError(w, http.StatusBadRequest, "Invalid request")
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return
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}
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identity, err = conn.HandlePOST(parseScopes(authReq.Scopes), r.PostFormValue("SAMLResponse"))
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identity, err = conn.HandlePOST(parseScopes(authReq.Scopes), r.PostFormValue("SAMLResponse"), authReq.ID)
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default:
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s.renderError(w, http.StatusInternalServerError, "Requested resource does not exist.")
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return
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