samlsp

package
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 Go to latest Published: May 25, 2021 License: BSD-2-Clause Imports: 21 Imported by: 0

Documentation

Overview

Package samlsp provides helpers that can be used to protect web services using SAML.

Index

Constants

This section is empty.

Variables

View Source 
var ErrNoSession = errors.New("saml: session not present")

ErrNoSession is the error returned when the remote user does not have a session

Functions

func AttributeFromContext 

func AttributeFromContext(ctx context.Context, name string) string

AttributeFromContext is a convenience method that returns the named attribute from the session, if available.

func ContextWithSession 

func ContextWithSession(ctx context.Context, session Session) context.Context

ContextWithSession returns a new context with session associated

func DefaultOnError 

func DefaultOnError(w http.ResponseWriter, r *http.Request, err error)

DefaultOnError is the default ErrorFunction implementation. It prints an message via the standard log package and returns a simple text "Forbidden" message to the user.

func DefaultServiceProvider 

func DefaultServiceProvider(opts Options) saml.ServiceProvider

DefaultServiceProvider returns the default saml.ServiceProvider for the provided options.

func FetchMetadata 

func FetchMetadata(ctx context.Context, httpClient *http.Client, metadataURL url.URL) (*saml.EntityDescriptor, error)

FetchMetadata returns metadata from an IDP metadata URL.

func ParseMetadata 

func ParseMetadata(data []byte) (*saml.EntityDescriptor, error)

ParseMetadata parses arbitrary SAML IDP metadata.

Note: this is needed because IDP metadata is sometimes wrapped in an <EntitiesDescriptor>, and sometimes the top level element is an <EntityDescriptor>.

func RequireAttribute 

func RequireAttribute(name, value string) func(http.Handler) http.Handler

RequireAttribute returns a middleware function that requires that the SAML attribute `name` be set to `value`. This can be used to require that a remote user be a member of a group. It relies on the Claims assigned to to the context in RequireAccount.

For example: 

goji.Use(m.RequireAccount)
goji.Use(RequireAttributeMiddleware("eduPersonAffiliation", "Staff"))

Types

type Attributes 

type Attributes map[string][]string

Attributes is a map of attributes provided in the SAML assertion

func (Attributes) Get 

func (a Attributes) Get(key string) string

Get returns the first attribute named `key` or an empty string if no such attributes is present.

type CookieRequestTracker 

type CookieRequestTracker struct {
	ServiceProvider *saml.ServiceProvider
	NamePrefix      string
	Codec           TrackedRequestCodec
	MaxAge          time.Duration
	RelayStateFunc  func(w http.ResponseWriter, r *http.Request) string
	SameSite        http.SameSite
}

CookieRequestTracker tracks requests by setting a uniquely named cookie for each request.

func DefaultRequestTracker 

func DefaultRequestTracker(opts Options, serviceProvider *saml.ServiceProvider) CookieRequestTracker

DefaultRequestTracker returns a new RequestTracker for the provided options, a CookieRequestTracker which uses cookies to track pending requests.

func (CookieRequestTracker) GetTrackedRequest 

func (t CookieRequestTracker) GetTrackedRequest(r *http.Request, index string) (*TrackedRequest, error)

GetTrackedRequest returns a pending tracked request.

func (CookieRequestTracker) GetTrackedRequests 

func (t CookieRequestTracker) GetTrackedRequests(r *http.Request) []TrackedRequest

GetTrackedRequests returns all the pending tracked requests

func (CookieRequestTracker) StopTrackingRequest 

func (t CookieRequestTracker) StopTrackingRequest(w http.ResponseWriter, r *http.Request, index string) error

StopTrackingRequest stops tracking the SAML request given by index, which is a string previously returned from TrackRequest

func (CookieRequestTracker) TrackRequest 

func (t CookieRequestTracker) TrackRequest(w http.ResponseWriter, r *http.Request, samlRequestID string) (string, error)

TrackRequest starts tracking the SAML request with the given ID. It returns an `index` that should be used as the RelayState in the SAMl request flow.

type CookieSessionProvider 

type CookieSessionProvider struct {
	Name     string
	Domain   string
	HTTPOnly bool
	Secure   bool
	SameSite http.SameSite
	MaxAge   time.Duration
	Codec    SessionCodec
}

CookieSessionProvider is an implementation of SessionProvider that stores session tokens in an HTTP cookie.

func DefaultSessionProvider 

func DefaultSessionProvider(opts Options) CookieSessionProvider

DefaultSessionProvider returns the default SessionProvider for the provided options, a CookieSessionProvider configured to store sessions in a cookie.

func (CookieSessionProvider) CreateSession 

func (c CookieSessionProvider) CreateSession(w http.ResponseWriter, r *http.Request, assertion *saml.Assertion) error

CreateSession is called when we have received a valid SAML assertion and should create a new session and modify the http response accordingly, e.g. by setting a cookie.

func (CookieSessionProvider) DeleteSession 

func (c CookieSessionProvider) DeleteSession(w http.ResponseWriter, r *http.Request) error

DeleteSession is called to modify the response such that it removed the current session, e.g. by deleting a cookie.

func (CookieSessionProvider) GetSession 

func (c CookieSessionProvider) GetSession(r *http.Request) (Session, error)

GetSession returns the current Session associated with the request, or ErrNoSession if there is no valid session.

type ErrorFunction 

type ErrorFunction func(w http.ResponseWriter, r *http.Request, err error)

ErrorFunction is a callback that is invoked to return an error to the web user.

type JWTSessionClaims 

type JWTSessionClaims struct {
	jwt.StandardClaims
	Attributes  Attributes `json:"attr"`
	SAMLSession bool       `json:"saml-session"`
}

JWTSessionClaims represents the JWT claims in the encoded session

func (JWTSessionClaims) GetAttributes 

func (c JWTSessionClaims) GetAttributes() Attributes

GetAttributes implements SessionWithAttributes. It returns the SAMl attributes.

type JWTSessionCodec 

type JWTSessionCodec struct {
	SigningMethod jwt.SigningMethod
	Audience      string
	Issuer        string
	MaxAge        time.Duration
	Key           *rsa.PrivateKey
}

JWTSessionCodec implements SessionCoded to encode and decode Sessions from the corresponding JWT.

func DefaultSessionCodec 

func DefaultSessionCodec(opts Options) JWTSessionCodec

DefaultSessionCodec returns the default SessionCodec for the provided options, a JWTSessionCodec configured to issue signed tokens.

func (JWTSessionCodec) Decode 

func (c JWTSessionCodec) Decode(signed string) (Session, error)

Decode parses the serialized session that may have been returned by Encode and returns a Session.

func (JWTSessionCodec) Encode 

func (c JWTSessionCodec) Encode(s Session) (string, error)

Encode returns a serialized version of the Session.

The provided session must be a JWTSessionClaims, otherwise this function will panic.

func (JWTSessionCodec) New 

func (c JWTSessionCodec) New(assertion *saml.Assertion) (Session, error)

New creates a Session from the SAML assertion.

The returned Session is a JWTSessionClaims.

type JWTTrackedRequestClaims 

type JWTTrackedRequestClaims struct {
	jwt.StandardClaims
	TrackedRequest
	SAMLAuthnRequest bool `json:"saml-authn-request"`
}

JWTTrackedRequestClaims represents the JWT claims for a tracked request.

type JWTTrackedRequestCodec 

type JWTTrackedRequestCodec struct {
	SigningMethod jwt.SigningMethod
	Audience      string
	Issuer        string
	MaxAge        time.Duration
	Key           *rsa.PrivateKey
}

JWTTrackedRequestCodec encodes TrackedRequests as signed JWTs

func DefaultTrackedRequestCodec 

func DefaultTrackedRequestCodec(opts Options) JWTTrackedRequestCodec

DefaultTrackedRequestCodec returns a new TrackedRequestCodec for the provided options, a JWTTrackedRequestCodec that uses a JWT to encode TrackedRequests.

func (JWTTrackedRequestCodec) Decode 

func (s JWTTrackedRequestCodec) Decode(signed string) (*TrackedRequest, error)

Decode returns a Tracked request from an encoded string.

func (JWTTrackedRequestCodec) Encode 

func (s JWTTrackedRequestCodec) Encode(value TrackedRequest) (string, error)

Encode returns an encoded string representing the TrackedRequest.

type Middleware 

type Middleware struct {
	ServiceProvider saml.ServiceProvider
	OnError         func(w http.ResponseWriter, r *http.Request, err error)
	Binding         string // either saml.HTTPPostBinding or saml.HTTPRedirectBinding
	RequestTracker  RequestTracker
	Session         SessionProvider
}

Middleware implements middleware than allows a web application to support SAML.

It implements http.Handler so that it can provide the metadata and ACS endpoints, typically /saml/metadata and /saml/acs, respectively.

It also provides middleware RequireAccount which redirects users to the auth process if they do not have session credentials.

When redirecting the user through the SAML auth flow, the middleware assigns a temporary cookie with a random name beginning with "saml_". The value of the cookie is a signed JSON Web Token containing the original URL requested and the SAML request ID. The random part of the name corresponds to the RelayState parameter passed through the SAML flow.

When validating the SAML response, the RelayState is used to look up the correct cookie, validate that the SAML request ID, and redirect the user back to their original URL.

Sessions are established by issuing a JSON Web Token (JWT) as a session cookie once the SAML flow has succeeded. The JWT token contains the authenticated attributes from the SAML assertion.

When the middleware receives a request with a valid session JWT it extracts the SAML attributes and modifies the http.Request object adding a Context object to the request context that contains attributes from the initial SAML assertion.

When issuing JSON Web Tokens, a signing key is required. Because the SAML service provider already has a private key, we borrow that key to sign the JWTs as well.

func New 

func New(opts Options) (*Middleware, error)

New creates a new Middleware with the default providers for the given options.

You can customize the behavior of the middleware in more detail by replacing and/or changing Session, RequestTracker, and ServiceProvider in the returned Middleware.

func (*Middleware) CreateSessionFromAssertion 

func (m *Middleware) CreateSessionFromAssertion(w http.ResponseWriter, r *http.Request, assertion *saml.Assertion)

CreateSessionFromAssertion is invoked by ServeHTTP when we have a new, valid SAML assertion.

func (*Middleware) HandleStartAuthFlow 

func (m *Middleware) HandleStartAuthFlow(w http.ResponseWriter, r *http.Request)

HandleStartAuthFlow is called to start the SAML authentication process.

func (*Middleware) RequireAccount 

func (m *Middleware) RequireAccount(handler http.Handler) http.Handler

RequireAccount is HTTP middleware that requires that each request be associated with a valid session. If the request is not associated with a valid session, then rather than serve the request, the middleware redirects the user to start the SAML auth flow.

func (*Middleware) ServeACS 

func (m *Middleware) ServeACS(w http.ResponseWriter, r *http.Request)

ServeACS handles requests for the SAML ACS endpoint.

func (*Middleware) ServeHTTP 

func (m *Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request)

ServeHTTP implements http.Handler and serves the SAML-specific HTTP endpoints on the URIs specified by m.ServiceProvider.MetadataURL and m.ServiceProvider.AcsURL.

func (*Middleware) ServeMetadata 

func (m *Middleware) ServeMetadata(w http.ResponseWriter, r *http.Request)

ServeMetadata handles requests for the SAML metadata endpoint.

type Options 

type Options struct {
	EntityID          string
	URL               url.URL
	Key               *rsa.PrivateKey
	Certificate       *x509.Certificate
	Intermediates     []*x509.Certificate
	AllowIDPInitiated bool
	IDPMetadata       *saml.EntityDescriptor
	SignRequest       bool
	ForceAuthn        bool // TODO(ross): this should be *bool
	CookieSameSite    http.SameSite
	RelayStateFunc    func(w http.ResponseWriter, r *http.Request) string
}

Options represents the parameters for creating a new middleware

type RequestTracker 

type RequestTracker interface {
	// TrackRequest starts tracking the SAML request with the given ID. It returns an
	// `index` that should be used as the RelayState in the SAMl request flow.
	TrackRequest(w http.ResponseWriter, r *http.Request, samlRequestID string) (index string, err error)

	// StopTrackingRequest stops tracking the SAML request given by index, which is a string
	// previously returned from TrackRequest
	StopTrackingRequest(w http.ResponseWriter, r *http.Request, index string) error

	// GetTrackedRequests returns all the pending tracked requests
	GetTrackedRequests(r *http.Request) []TrackedRequest

	// GetTrackedRequest returns a pending tracked request.
	GetTrackedRequest(r *http.Request, index string) (*TrackedRequest, error)
}

RequestTracker tracks pending authentication requests.

There are two main reasons for this:

  1. When the middleware initiates an authentication request it must track the original URL in order to redirect the user to the right place after the authentication completes.
  1. After the authentication completes, we want to ensure that the user presenting the assertion is actually the one the request it, to mitigate request forgeries.

type Session 

type Session interface{}

Session is an interface implemented to contain a session.

func SessionFromContext 

func SessionFromContext(ctx context.Context) Session

SessionFromContext returns the session associated with ctx, or nil if no session are associated

type SessionCodec 

type SessionCodec interface {
	// New creates a Session from the SAML assertion.
	New(assertion *saml.Assertion) (Session, error)

	// Encode returns a serialized version of the Session.
	//
	// Note: When implementing this function, it is reasonable to expect that
	// Session is of the exact type returned by New(), and panic if it is not.
	Encode(s Session) (string, error)

	// Decode parses the serialized session that may have been returned by Encode
	// and returns a Session.
	Decode(string) (Session, error)
}

SessionCodec is an interface to convert SAML assertions to a Session. The default implementation uses JWTs, JWTSessionCodec.

type SessionProvider 

type SessionProvider interface {
	// CreateSession is called when we have received a valid SAML assertion and
	// should create a new session and modify the http response accordingly, e.g. by
	// setting a cookie.
	CreateSession(w http.ResponseWriter, r *http.Request, assertion *saml.Assertion) error

	// DeleteSession is called to modify the response such that it removed the current
	// session, e.g. by deleting a cookie.
	DeleteSession(w http.ResponseWriter, r *http.Request) error

	// GetSession returns the current Session associated with the request, or
	// ErrNoSession if there is no valid session.
	GetSession(r *http.Request) (Session, error)
}

SessionProvider is an interface implemented by types that can track the active session of a user. The default implementation is CookieSessionProvider

type SessionWithAttributes 

type SessionWithAttributes interface {
	Session
	GetAttributes() Attributes
}

SessionWithAttributes is a session that can expose the attributes provided by the SAML identity provider.

type TrackedRequest 

type TrackedRequest struct {
	Index         string `json:"-"`
	SAMLRequestID string `json:"id"`
	URI           string `json:"uri"`
}

TrackedRequest holds the data we store for each pending request.

type TrackedRequestCodec 

type TrackedRequestCodec interface {
	// Encode returns an encoded string representing the TrackedRequest.
	Encode(value TrackedRequest) (string, error)

	// Decode returns a Tracked request from an encoded string.
	Decode(signed string) (*TrackedRequest, error)
}

TrackedRequestCodec handles encoding and decoding of a TrackedRequest.

Source Files

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