OAuth2 Authorization Code Grant Flow #247
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,332 @@ | ||
| package accesscontrol | ||
|
|
||
| import ( | ||
| "context" | ||
| "crypto/sha256" | ||
| "encoding/base64" | ||
| "encoding/json" | ||
| "io/ioutil" | ||
| "net/http" | ||
| "strings" | ||
| "time" | ||
|
|
||
| "github.com/dgrijalva/jwt-go/v4" | ||
|
|
||
| "github.com/avenga/couper/config" | ||
| "github.com/avenga/couper/config/request" | ||
| "github.com/avenga/couper/errors" | ||
| "github.com/avenga/couper/eval" | ||
| "github.com/avenga/couper/eval/lib" | ||
| "github.com/avenga/couper/handler/transport" | ||
| "github.com/avenga/couper/internal/seetie" | ||
| ) | ||
|
|
||
| var _ AccessControl = &OAuth2Callback{} | ||
|
|
||
| type OAuth2Callback struct { | ||
| config *config.OAuth2AC | ||
| oauth2 *transport.OAuth2 | ||
| jwtParser *jwt.Parser | ||
| } | ||
|
|
||
| // NewOAuth2Callback creates a new AC-OAuth2 object | ||
| func NewOAuth2Callback(conf *config.OAuth2AC, oauth2 *transport.OAuth2) (*OAuth2Callback, error) { | ||
| confErr := errors.Configuration.Label(conf.Name) | ||
|
|
||
| const grantType = "authorization_code" | ||
| if conf.GrantType != grantType { | ||
| return nil, confErr.Messagef("grant_type %s not supported", conf.GrantType) | ||
| } | ||
| if conf.Pkce == nil && conf.Csrf == nil { | ||
| return nil, confErr.Message("CSRF protection not configured") | ||
| } | ||
| if conf.Csrf != nil { | ||
| if conf.Csrf.TokenParam != "state" && conf.Csrf.TokenParam != "nonce" { | ||
| return nil, confErr.Messagef("csrf_token_param %s not supported", conf.Csrf.TokenParam) | ||
| } | ||
| content, _, diags := conf.Csrf.HCLBody().PartialContent(conf.Csrf.Schema(true)) | ||
| if diags.HasErrors() { | ||
| return nil, errors.Evaluation.With(diags) | ||
| } | ||
| conf.Csrf.Content = content | ||
| } | ||
| if conf.Pkce != nil { | ||
| if conf.Pkce.CodeChallengeMethod != lib.CcmPlain && conf.Pkce.CodeChallengeMethod != lib.CcmS256 { | ||
| return nil, confErr.Messagef("code_challenge_method %s not supported", conf.Pkce.CodeChallengeMethod) | ||
| } | ||
| content, _, diags := conf.Pkce.HCLBody().PartialContent(conf.Pkce.Schema(true)) | ||
| if diags.HasErrors() { | ||
| return nil, errors.Evaluation.With(diags) | ||
| } | ||
| conf.Pkce.Content = content | ||
| } | ||
|
|
||
| options := []jwt.ParserOption{ | ||
| // jwt.WithValidMethods([]string{algo.String()}), | ||
| jwt.WithLeeway(time.Second), | ||
| // 2. The Issuer Identifier for the OpenID Provider (which is typically | ||
| // obtained during Discovery) MUST exactly match the value of the iss | ||
| // (issuer) Claim. | ||
| jwt.WithIssuer(conf.Issuer), | ||
| // 3. The Client MUST validate that the aud (audience) Claim contains its | ||
| // client_id value registered at the Issuer identified by the iss | ||
| // (issuer) Claim as an audience. The aud (audience) Claim MAY contain | ||
| // an array with more than one element. The ID Token MUST be rejected if | ||
| // the ID Token does not list the Client as a valid audience, or if it | ||
| // contains additional audiences not trusted by the Client. | ||
| jwt.WithAudience(conf.ClientID), | ||
| } | ||
| jwtParser := jwt.NewParser(options...) | ||
|
|
||
| return &OAuth2Callback{ | ||
| config: conf, | ||
| jwtParser: jwtParser, | ||
| oauth2: oauth2, | ||
| }, nil | ||
| } | ||
|
|
||
| // Validate implements the AccessControl interface | ||
| func (oa *OAuth2Callback) Validate(req *http.Request) error { | ||
| if req.Method != http.MethodGet { | ||
| return errors.Oauth2.Messagef("wrong method: %s", req.Method) | ||
| } | ||
|
|
||
| query := req.URL.Query() | ||
| code := query.Get("code") | ||
| if code == "" { | ||
| return errors.Oauth2.Messagef("missing code query parameter; query='%s'", req.URL.RawQuery) | ||
malud marked this conversation as resolved.
Show resolved
Hide resolved
|
||
| } | ||
|
|
||
| requestConfig, err := oa.oauth2.GetRequestConfig(req) | ||
| if err != nil { | ||
| return errors.Oauth2.With(err) | ||
| } | ||
|
|
||
| evalContext, _ := req.Context().Value(eval.ContextType).(*eval.Context) | ||
|
|
||
| if oa.config.Pkce != nil { | ||
| v, _ := oa.config.Pkce.Content.Attributes["code_verifier_value"] | ||
| ctyVal, _ := v.Expr.Value(evalContext.HCLContext()) | ||
| codeVerifierValue := strings.TrimSpace(seetie.ValueToString(ctyVal)) | ||
| if codeVerifierValue == "" { | ||
| return errors.Oauth2.Messagef("Empty PKCE code_verifier_value") | ||
| } | ||
| requestConfig.CodeVerifier = &codeVerifierValue | ||
| } | ||
|
|
||
| var csrfToken, csrfTokenValue string | ||
| if oa.config.Csrf != nil { | ||
| v, _ := oa.config.Csrf.Content.Attributes["token_value"] | ||
| ctyVal, _ := v.Expr.Value(evalContext.HCLContext()) | ||
| csrfTokenValue = strings.TrimSpace(seetie.ValueToString(ctyVal)) | ||
| if csrfTokenValue == "" { | ||
| return errors.Oauth2.Messagef("Empty CSRF token_value") | ||
| } | ||
| csrfToken = Base64url_s256(csrfTokenValue) | ||
|
|
||
| // validate state param value against CSRF token | ||
| if oa.config.Csrf.TokenParam == "state" { | ||
| csrfTokenFromParam := query.Get(oa.config.Csrf.TokenParam) | ||
| if csrfTokenFromParam == "" { | ||
| return errors.Oauth2.Messagef("missing state query parameter; query='%s'", req.URL.RawQuery) | ||
| } | ||
|
|
||
| if csrfToken != csrfTokenFromParam { | ||
| return errors.Oauth2.Messagef("CSRF token mismatch: '%s' (from query param) vs. '%s' (s256: '%s')", csrfTokenFromParam, csrfTokenValue, csrfToken) | ||
johakoch marked this conversation as resolved.
Show resolved
Hide resolved
|
||
| } | ||
| } | ||
| } | ||
|
|
||
| requestConfig.Code = &code | ||
|
There was a problem hiding this comment. Maybe this could be a task (read/assign query) for There was a problem hiding this comment. As |
||
| requestConfig.RedirectURI = oa.config.RedirectURI | ||
|
|
||
| tokenResponse, err := oa.oauth2.RequestToken(req.Context(), requestConfig) | ||
| if err != nil { | ||
| return errors.Oauth2.Message("requesting token failed").With(err) | ||
| } | ||
|
|
||
| tokenData, accessToken, err := transport.ParseAccessToken(tokenResponse) | ||
| if err != nil { | ||
| return errors.Oauth2.Messagef("parsing token response JSON failed, response='%s'", string(tokenResponse)).With(err) | ||
| } | ||
|
|
||
| ctx := req.Context() | ||
| if idTokenString, ok := tokenData["id_token"].(string); ok { | ||
| idToken, _, err := oa.jwtParser.ParseUnverified(idTokenString, jwt.MapClaims{}) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| // 2. ID Token | ||
| // iss | ||
| // REQUIRED. | ||
| // aud | ||
| // REQUIRED. | ||
| // 3.1.3.7. ID Token Validation | ||
| // 3. The Client MUST validate that the aud (audience) Claim contains | ||
| // its client_id value registered at the Issuer identified by the | ||
| // iss (issuer) Claim as an audience. The aud (audience) Claim MAY | ||
| // contain an array with more than one element. The ID Token MUST | ||
| // be rejected if the ID Token does not list the Client as a valid | ||
| // audience, or if it contains additional audiences not trusted by | ||
| // the Client. | ||
| if err := idToken.Claims.Valid(oa.jwtParser.ValidationHelper); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| idtc, err := oa.validateIdTokenClaims(idToken.Claims, csrfToken, csrfTokenValue, ctx, accessToken) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| tokenData["id_token_claims"] = idtc | ||
| } | ||
|
|
||
| acMap, ok := ctx.Value(request.AccessControls).(map[string]interface{}) | ||
| if !ok { | ||
| acMap = make(map[string]interface{}) | ||
| } | ||
| acMap[oa.config.Name] = tokenData | ||
| ctx = context.WithValue(ctx, request.AccessControls, acMap) | ||
| *req = *req.WithContext(ctx) | ||
|
|
||
| return nil | ||
| } | ||
|
|
||
| func (oa *OAuth2Callback) validateIdTokenClaims(claims jwt.Claims, csrfToken, csrfTokenValue string, ctx context.Context, accessToken string) (map[string]interface{}, error) { | ||
johakoch marked this conversation as resolved.
Show resolved
Hide resolved
|
||
| var idTokenClaims jwt.MapClaims | ||
| if tc, ok := claims.(jwt.MapClaims); ok { | ||
| idTokenClaims = tc | ||
| } | ||
|
|
||
| // 2. ID Token | ||
| // exp | ||
| // REQUIRED. | ||
| if _, expExists := idTokenClaims["exp"]; !expExists { | ||
| return nil, errors.Oauth2.Messagef("missing exp claim in ID token, claims='%#v'", idTokenClaims) | ||
| } | ||
| // iat | ||
| // REQUIRED. | ||
| if _, iatExists := idTokenClaims["iat"]; !iatExists { | ||
| return nil, errors.Oauth2.Messagef("missing iat claim in ID token, claims='%#v'", idTokenClaims) | ||
| } | ||
|
|
||
| // 3.1.3.7. ID Token Validation | ||
| // 4. If the ID Token contains multiple audiences, the Client SHOULD verify | ||
| // that an azp Claim is present. | ||
| azp, azpExists := idTokenClaims["azp"] | ||
| if auds, audsOK := idTokenClaims["aud"].([]interface{}); audsOK && len(auds) > 1 && !azpExists { | ||
| return nil, errors.Oauth2.Messagef("missing azp claim in ID token, claims='%#v'", idTokenClaims) | ||
| } | ||
| // 5. If an azp (authorized party) Claim is present, the Client SHOULD | ||
| // verify that its client_id is the Claim Value. | ||
| if azpExists && azp != oa.config.ClientID { | ||
| return nil, errors.Oauth2.Messagef("azp claim / client ID mismatch, azp = '%s', client ID = '%s'", azp, oa.config.ClientID) | ||
| } | ||
|
|
||
| // validate nonce claim value against CSRF token | ||
| if oa.config.Csrf != nil && oa.config.Csrf.TokenParam == "nonce" { | ||
| // 11. If a nonce value was sent in the Authentication Request, a nonce | ||
| // Claim MUST be present and its value checked to verify that it is the | ||
| // same value as the one that was sent in the Authentication Request. | ||
| // The Client SHOULD check the nonce value for replay attacks. The | ||
| // precise method for detecting replay attacks is Client specific. | ||
| var nonce string | ||
| if n, ok := idTokenClaims["nonce"].(string); ok { | ||
| nonce = n | ||
| } else { | ||
| return nil, errors.Oauth2.Messagef("missing nonce claim in ID token, claims='%#v'", idTokenClaims) | ||
| } | ||
|
|
||
| if csrfToken != nonce { | ||
| return nil, errors.Oauth2.Messagef("CSRF token mismatch: '%s' (from nonce claim) vs. '%s' (s256: '%s')", nonce, csrfTokenValue, csrfToken) | ||
| } | ||
| } | ||
|
|
||
| // 2. ID Token | ||
| // sub | ||
| // REQUIRED. | ||
| var subIdtoken string | ||
| if s, ok := idTokenClaims["sub"].(string); ok { | ||
| subIdtoken = s | ||
| } else { | ||
| return nil, errors.Oauth2.Messagef("missing sub claim in ID token, claims='%#v'", idTokenClaims) | ||
| } | ||
|
|
||
| userinfoResponse, err := oa.requestUserinfo(ctx, accessToken) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| userinfoResponseString := string(userinfoResponse) | ||
| var userinfoData map[string]interface{} | ||
| err = json.Unmarshal(userinfoResponse, &userinfoData) | ||
| if err != nil { | ||
| return nil, errors.Oauth2.Messagef("parsing userinfo response JSON failed, response='%s'", userinfoResponseString).With(err) | ||
| } | ||
|
|
||
| var subUserinfo string | ||
| if s, ok := userinfoData["sub"].(string); ok { | ||
| subUserinfo = s | ||
| } else { | ||
| return nil, errors.Oauth2.Messagef("missing sub property in userinfo response, response='%s'", userinfoResponseString) | ||
| } | ||
|
|
||
| if subIdtoken != subUserinfo { | ||
| return nil, errors.Oauth2.Messagef("subject mismatch, in ID token '%s', in userinfo response '%s'", subIdtoken, subUserinfo) | ||
| } | ||
|
|
||
| return idTokenClaims, nil | ||
| } | ||
|
|
||
| func (oa *OAuth2Callback) requestUserinfo(ctx context.Context, accessToken string) ([]byte, error) { | ||
| userinfoReq, err := oa.newUserinfoRequest(ctx, accessToken) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| userinfoRes, err := oa.oauth2.Backend.RoundTrip(userinfoReq) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| userinfoResBytes, err := ioutil.ReadAll(userinfoRes.Body) | ||
| if err != nil { | ||
| return nil, errors.Backend.Label(oa.config.Reference()).Message("userinfo request read error").With(err) | ||
| } | ||
|
|
||
| if userinfoRes.StatusCode != http.StatusOK { | ||
| return nil, errors.Backend.Label(oa.config.Reference()).Messagef("userinfo request failed, response='%s'", string(userinfoResBytes)) | ||
| } | ||
|
|
||
| return userinfoResBytes, nil | ||
| } | ||
|
|
||
| func (oa *OAuth2Callback) newUserinfoRequest(ctx context.Context, accessToken string) (*http.Request, error) { | ||
| url, err := eval.GetContextAttribute(oa.config.HCLBody(), ctx, "userinfo_endpoint") | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| if url == "" { | ||
| return nil, errors.Oauth2.Messagef("missing userinfo_endpoint in config") | ||
| } | ||
|
|
||
| // url will be configured via backend roundtrip | ||
| outreq, err := http.NewRequest(http.MethodGet, url, nil) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| outreq.Header.Set("Authorization", "Bearer "+accessToken) | ||
|
|
||
| outCtx := context.WithValue(ctx, request.URLAttribute, url) | ||
|
|
||
| return outreq.WithContext(outCtx), nil | ||
| } | ||
|
|
||
| func Base64url_s256(value string) string { | ||
johakoch marked this conversation as resolved.
Show resolved
Hide resolved
|
||
| h := sha256.New() | ||
| h.Write([]byte(value)) | ||
| return base64.RawURLEncoding.EncodeToString(h.Sum(nil)) | ||
| } | ||
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
This applies to all Oauth2 errors, could we add more context e.g.
oa.conf.Nameas.Label(...)?There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Should the caller give the context? Or the callee?