ContainerImage.Pinniped/internal/oidc/callback/callback_handler.go

171 lines
5.7 KiB
Go

// Copyright 2020-2021 the Pinniped contributors. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
// Package callback provides a handler for the OIDC callback endpoint.
package callback
import (
"crypto/subtle"
"net/http"
"net/url"
"github.com/ory/fosite"
"go.pinniped.dev/internal/httputil/httperr"
"go.pinniped.dev/internal/httputil/securityheader"
"go.pinniped.dev/internal/oidc"
"go.pinniped.dev/internal/oidc/csrftoken"
"go.pinniped.dev/internal/oidc/downstreamsession"
"go.pinniped.dev/internal/oidc/provider"
"go.pinniped.dev/internal/oidc/provider/formposthtml"
"go.pinniped.dev/internal/plog"
)
func NewHandler(
upstreamIDPs oidc.UpstreamOIDCIdentityProvidersLister,
oauthHelper fosite.OAuth2Provider,
stateDecoder, cookieDecoder oidc.Decoder,
redirectURI string,
) http.Handler {
handler := httperr.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
state, err := validateRequest(r, stateDecoder, cookieDecoder)
if err != nil {
return err
}
upstreamIDPConfig := findUpstreamIDPConfig(state.UpstreamName, upstreamIDPs)
if upstreamIDPConfig == nil {
plog.Warning("upstream provider not found")
return httperr.New(http.StatusUnprocessableEntity, "upstream provider not found")
}
downstreamAuthParams, err := url.ParseQuery(state.AuthParams)
if err != nil {
plog.Error("error reading state downstream auth params", err)
return httperr.New(http.StatusBadRequest, "error reading state downstream auth params")
}
// Recreate enough of the original authorize request so we can pass it to NewAuthorizeRequest().
reconstitutedAuthRequest := &http.Request{Form: downstreamAuthParams}
authorizeRequester, err := oauthHelper.NewAuthorizeRequest(r.Context(), reconstitutedAuthRequest)
if err != nil {
plog.Error("error using state downstream auth params", err)
return httperr.New(http.StatusBadRequest, "error using state downstream auth params")
}
// Automatically grant the openid, offline_access, and pinniped:request-audience scopes, but only if they were requested.
downstreamsession.GrantScopesIfRequested(authorizeRequester)
token, err := upstreamIDPConfig.ExchangeAuthcodeAndValidateTokens(
r.Context(),
authcode(r),
state.PKCECode,
state.Nonce,
redirectURI,
)
if err != nil {
plog.WarningErr("error exchanging and validating upstream tokens", err, "upstreamName", upstreamIDPConfig.GetName())
return httperr.New(http.StatusBadGateway, "error exchanging and validating upstream tokens")
}
subject, username, groups, err := downstreamsession.GetDownstreamIdentityFromUpstreamIDToken(upstreamIDPConfig, token.IDToken.Claims)
if err != nil {
return httperr.Wrap(http.StatusUnprocessableEntity, err.Error(), err)
}
openIDSession := downstreamsession.MakeDownstreamSession(subject, username, groups)
authorizeResponder, err := oauthHelper.NewAuthorizeResponse(r.Context(), authorizeRequester, openIDSession)
if err != nil {
plog.WarningErr("error while generating and saving authcode", err, "upstreamName", upstreamIDPConfig.GetName())
return httperr.Wrap(http.StatusInternalServerError, "error while generating and saving authcode", err)
}
oauthHelper.WriteAuthorizeResponse(w, authorizeRequester, authorizeResponder)
return nil
})
return securityheader.WrapWithCustomCSP(handler, formposthtml.ContentSecurityPolicy())
}
func authcode(r *http.Request) string {
return r.FormValue("code")
}
func validateRequest(r *http.Request, stateDecoder, cookieDecoder oidc.Decoder) (*oidc.UpstreamStateParamData, error) {
if r.Method != http.MethodGet {
return nil, httperr.Newf(http.StatusMethodNotAllowed, "%s (try GET)", r.Method)
}
csrfValue, err := readCSRFCookie(r, cookieDecoder)
if err != nil {
plog.InfoErr("error reading CSRF cookie", err)
return nil, err
}
if authcode(r) == "" {
plog.Info("code param not found")
return nil, httperr.New(http.StatusBadRequest, "code param not found")
}
if r.FormValue("state") == "" {
plog.Info("state param not found")
return nil, httperr.New(http.StatusBadRequest, "state param not found")
}
state, err := readState(r, stateDecoder)
if err != nil {
plog.InfoErr("error reading state", err)
return nil, err
}
if subtle.ConstantTimeCompare([]byte(state.CSRFToken), []byte(csrfValue)) != 1 {
plog.InfoErr("CSRF value does not match", err)
return nil, httperr.Wrap(http.StatusForbidden, "CSRF value does not match", err)
}
return state, nil
}
func findUpstreamIDPConfig(upstreamName string, upstreamIDPs oidc.UpstreamOIDCIdentityProvidersLister) provider.UpstreamOIDCIdentityProviderI {
for _, p := range upstreamIDPs.GetOIDCIdentityProviders() {
if p.GetName() == upstreamName {
return p
}
}
return nil
}
func readCSRFCookie(r *http.Request, cookieDecoder oidc.Decoder) (csrftoken.CSRFToken, error) {
receivedCSRFCookie, err := r.Cookie(oidc.CSRFCookieName)
if err != nil {
// Error means that the cookie was not found
return "", httperr.Wrap(http.StatusForbidden, "CSRF cookie is missing", err)
}
var csrfFromCookie csrftoken.CSRFToken
err = cookieDecoder.Decode(oidc.CSRFCookieEncodingName, receivedCSRFCookie.Value, &csrfFromCookie)
if err != nil {
return "", httperr.Wrap(http.StatusForbidden, "error reading CSRF cookie", err)
}
return csrfFromCookie, nil
}
func readState(r *http.Request, stateDecoder oidc.Decoder) (*oidc.UpstreamStateParamData, error) {
var state oidc.UpstreamStateParamData
if err := stateDecoder.Decode(
oidc.UpstreamStateParamEncodingName,
r.FormValue("state"),
&state,
); err != nil {
return nil, httperr.New(http.StatusBadRequest, "error reading state")
}
if state.FormatVersion != oidc.UpstreamStateParamFormatVersion {
return nil, httperr.New(http.StatusUnprocessableEntity, "state format version is invalid")
}
return &state, nil
}