forgejo/routers/user/oauth.go
Johnny Oskarsson a07e67d9cc
Minimal OpenID Connect implementation (#14139)
This is "minimal" in the sense that only the Authorization Code Flow
from OpenID Connect Core is implemented.  No discovery, no configuration
endpoint, and no user scope management.

OpenID Connect is an extension to the (already implemented) OAuth 2.0
protocol, and essentially an `id_token` JWT is added to the access token
endpoint response when using the Authorization Code Flow.  I also added
support for the "nonce" field since it is required to be used in the
id_token if the client decides to include it in its initial request.

In order to enable this extension an OAuth 2.0 scope containing
"openid" is needed. Other OAuth 2.0 requests should not be impacted by
this change.

This minimal implementation is enough to enable single sign-on (SSO)
for other sites, e.g. by using something like `mod_auth_openidc` to
only allow access to a CI server if a user has logged into Gitea.

Fixes: #1310

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
2021-01-02 00:33:27 +08:00

558 lines
18 KiB
Go

// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package user
import (
"encoding/base64"
"fmt"
"html"
"net/url"
"strings"
"code.gitea.io/gitea/models"
"code.gitea.io/gitea/modules/auth"
"code.gitea.io/gitea/modules/base"
"code.gitea.io/gitea/modules/context"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/timeutil"
"gitea.com/macaron/binding"
"github.com/dgrijalva/jwt-go"
)
const (
tplGrantAccess base.TplName = "user/auth/grant"
tplGrantError base.TplName = "user/auth/grant_error"
)
// TODO move error and responses to SDK or models
// AuthorizeErrorCode represents an error code specified in RFC 6749
type AuthorizeErrorCode string
const (
// ErrorCodeInvalidRequest represents the according error in RFC 6749
ErrorCodeInvalidRequest AuthorizeErrorCode = "invalid_request"
// ErrorCodeUnauthorizedClient represents the according error in RFC 6749
ErrorCodeUnauthorizedClient AuthorizeErrorCode = "unauthorized_client"
// ErrorCodeAccessDenied represents the according error in RFC 6749
ErrorCodeAccessDenied AuthorizeErrorCode = "access_denied"
// ErrorCodeUnsupportedResponseType represents the according error in RFC 6749
ErrorCodeUnsupportedResponseType AuthorizeErrorCode = "unsupported_response_type"
// ErrorCodeInvalidScope represents the according error in RFC 6749
ErrorCodeInvalidScope AuthorizeErrorCode = "invalid_scope"
// ErrorCodeServerError represents the according error in RFC 6749
ErrorCodeServerError AuthorizeErrorCode = "server_error"
// ErrorCodeTemporaryUnavailable represents the according error in RFC 6749
ErrorCodeTemporaryUnavailable AuthorizeErrorCode = "temporarily_unavailable"
)
// AuthorizeError represents an error type specified in RFC 6749
type AuthorizeError struct {
ErrorCode AuthorizeErrorCode `json:"error" form:"error"`
ErrorDescription string
State string
}
// Error returns the error message
func (err AuthorizeError) Error() string {
return fmt.Sprintf("%s: %s", err.ErrorCode, err.ErrorDescription)
}
// AccessTokenErrorCode represents an error code specified in RFC 6749
type AccessTokenErrorCode string
const (
// AccessTokenErrorCodeInvalidRequest represents an error code specified in RFC 6749
AccessTokenErrorCodeInvalidRequest AccessTokenErrorCode = "invalid_request"
// AccessTokenErrorCodeInvalidClient represents an error code specified in RFC 6749
AccessTokenErrorCodeInvalidClient = "invalid_client"
// AccessTokenErrorCodeInvalidGrant represents an error code specified in RFC 6749
AccessTokenErrorCodeInvalidGrant = "invalid_grant"
// AccessTokenErrorCodeUnauthorizedClient represents an error code specified in RFC 6749
AccessTokenErrorCodeUnauthorizedClient = "unauthorized_client"
// AccessTokenErrorCodeUnsupportedGrantType represents an error code specified in RFC 6749
AccessTokenErrorCodeUnsupportedGrantType = "unsupported_grant_type"
// AccessTokenErrorCodeInvalidScope represents an error code specified in RFC 6749
AccessTokenErrorCodeInvalidScope = "invalid_scope"
)
// AccessTokenError represents an error response specified in RFC 6749
type AccessTokenError struct {
ErrorCode AccessTokenErrorCode `json:"error" form:"error"`
ErrorDescription string `json:"error_description"`
}
// Error returns the error message
func (err AccessTokenError) Error() string {
return fmt.Sprintf("%s: %s", err.ErrorCode, err.ErrorDescription)
}
// TokenType specifies the kind of token
type TokenType string
const (
// TokenTypeBearer represents a token type specified in RFC 6749
TokenTypeBearer TokenType = "bearer"
// TokenTypeMAC represents a token type specified in RFC 6749
TokenTypeMAC = "mac"
)
// AccessTokenResponse represents a successful access token response
type AccessTokenResponse struct {
AccessToken string `json:"access_token"`
TokenType TokenType `json:"token_type"`
ExpiresIn int64 `json:"expires_in"`
RefreshToken string `json:"refresh_token"`
IDToken string `json:"id_token,omitempty"`
}
func newAccessTokenResponse(grant *models.OAuth2Grant, clientSecret string) (*AccessTokenResponse, *AccessTokenError) {
if setting.OAuth2.InvalidateRefreshTokens {
if err := grant.IncreaseCounter(); err != nil {
return nil, &AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidGrant,
ErrorDescription: "cannot increase the grant counter",
}
}
}
// generate access token to access the API
expirationDate := timeutil.TimeStampNow().Add(setting.OAuth2.AccessTokenExpirationTime)
accessToken := &models.OAuth2Token{
GrantID: grant.ID,
Type: models.TypeAccessToken,
StandardClaims: jwt.StandardClaims{
ExpiresAt: expirationDate.AsTime().Unix(),
},
}
signedAccessToken, err := accessToken.SignToken()
if err != nil {
return nil, &AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot sign token",
}
}
// generate refresh token to request an access token after it expired later
refreshExpirationDate := timeutil.TimeStampNow().Add(setting.OAuth2.RefreshTokenExpirationTime * 60 * 60).AsTime().Unix()
refreshToken := &models.OAuth2Token{
GrantID: grant.ID,
Counter: grant.Counter,
Type: models.TypeRefreshToken,
StandardClaims: jwt.StandardClaims{
ExpiresAt: refreshExpirationDate,
},
}
signedRefreshToken, err := refreshToken.SignToken()
if err != nil {
return nil, &AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot sign token",
}
}
// generate OpenID Connect id_token
signedIDToken := ""
if grant.ScopeContains("openid") {
app, err := models.GetOAuth2ApplicationByID(grant.ApplicationID)
if err != nil {
return nil, &AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot find application",
}
}
idToken := &models.OIDCToken{
StandardClaims: jwt.StandardClaims{
ExpiresAt: expirationDate.AsTime().Unix(),
Issuer: setting.AppURL,
Audience: app.ClientID,
Subject: fmt.Sprint(grant.UserID),
},
Nonce: grant.Nonce,
}
signedIDToken, err = idToken.SignToken(clientSecret)
if err != nil {
return nil, &AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot sign token",
}
}
}
return &AccessTokenResponse{
AccessToken: signedAccessToken,
TokenType: TokenTypeBearer,
ExpiresIn: setting.OAuth2.AccessTokenExpirationTime,
RefreshToken: signedRefreshToken,
IDToken: signedIDToken,
}, nil
}
// AuthorizeOAuth manages authorize requests
func AuthorizeOAuth(ctx *context.Context, form auth.AuthorizationForm) {
errs := binding.Errors{}
errs = form.Validate(ctx.Context, errs)
if len(errs) > 0 {
errstring := ""
for _, e := range errs {
errstring += e.Error() + "\n"
}
ctx.ServerError("AuthorizeOAuth: Validate: ", fmt.Errorf("errors occurred during validation: %s", errstring))
return
}
app, err := models.GetOAuth2ApplicationByClientID(form.ClientID)
if err != nil {
if models.IsErrOauthClientIDInvalid(err) {
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeUnauthorizedClient,
ErrorDescription: "Client ID not registered",
State: form.State,
}, "")
return
}
ctx.ServerError("GetOAuth2ApplicationByClientID", err)
return
}
if err := app.LoadUser(); err != nil {
ctx.ServerError("LoadUser", err)
return
}
if !app.ContainsRedirectURI(form.RedirectURI) {
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeInvalidRequest,
ErrorDescription: "Unregistered Redirect URI",
State: form.State,
}, "")
return
}
if form.ResponseType != "code" {
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeUnsupportedResponseType,
ErrorDescription: "Only code response type is supported.",
State: form.State,
}, form.RedirectURI)
return
}
// pkce support
switch form.CodeChallengeMethod {
case "S256":
case "plain":
if err := ctx.Session.Set("CodeChallengeMethod", form.CodeChallengeMethod); err != nil {
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeServerError,
ErrorDescription: "cannot set code challenge method",
State: form.State,
}, form.RedirectURI)
return
}
if err := ctx.Session.Set("CodeChallengeMethod", form.CodeChallenge); err != nil {
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeServerError,
ErrorDescription: "cannot set code challenge",
State: form.State,
}, form.RedirectURI)
return
}
// Here we're just going to try to release the session early
if err := ctx.Session.Release(); err != nil {
// we'll tolerate errors here as they *should* get saved elsewhere
log.Error("Unable to save changes to the session: %v", err)
}
case "":
break
default:
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeInvalidRequest,
ErrorDescription: "unsupported code challenge method",
State: form.State,
}, form.RedirectURI)
return
}
grant, err := app.GetGrantByUserID(ctx.User.ID)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
return
}
// Redirect if user already granted access
if grant != nil {
code, err := grant.GenerateNewAuthorizationCode(form.RedirectURI, form.CodeChallenge, form.CodeChallengeMethod)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
return
}
redirect, err := code.GenerateRedirectURI(form.State)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
return
}
// Update nonce to reflect the new session
if len(form.Nonce) > 0 {
err := grant.SetNonce(form.Nonce)
if err != nil {
log.Error("Unable to update nonce: %v", err)
}
}
ctx.Redirect(redirect.String(), 302)
return
}
// show authorize page to grant access
ctx.Data["Application"] = app
ctx.Data["RedirectURI"] = form.RedirectURI
ctx.Data["State"] = form.State
ctx.Data["Scope"] = form.Scope
ctx.Data["Nonce"] = form.Nonce
ctx.Data["ApplicationUserLink"] = "<a href=\"" + html.EscapeString(setting.AppURL) + html.EscapeString(url.PathEscape(app.User.LowerName)) + "\">@" + html.EscapeString(app.User.Name) + "</a>"
ctx.Data["ApplicationRedirectDomainHTML"] = "<strong>" + html.EscapeString(form.RedirectURI) + "</strong>"
// TODO document SESSION <=> FORM
err = ctx.Session.Set("client_id", app.ClientID)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
log.Error(err.Error())
return
}
err = ctx.Session.Set("redirect_uri", form.RedirectURI)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
log.Error(err.Error())
return
}
err = ctx.Session.Set("state", form.State)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
log.Error(err.Error())
return
}
// Here we're just going to try to release the session early
if err := ctx.Session.Release(); err != nil {
// we'll tolerate errors here as they *should* get saved elsewhere
log.Error("Unable to save changes to the session: %v", err)
}
ctx.HTML(200, tplGrantAccess)
}
// GrantApplicationOAuth manages the post request submitted when a user grants access to an application
func GrantApplicationOAuth(ctx *context.Context, form auth.GrantApplicationForm) {
if ctx.Session.Get("client_id") != form.ClientID || ctx.Session.Get("state") != form.State ||
ctx.Session.Get("redirect_uri") != form.RedirectURI {
ctx.Error(400)
return
}
app, err := models.GetOAuth2ApplicationByClientID(form.ClientID)
if err != nil {
ctx.ServerError("GetOAuth2ApplicationByClientID", err)
return
}
grant, err := app.CreateGrant(ctx.User.ID, form.Scope)
if err != nil {
handleAuthorizeError(ctx, AuthorizeError{
State: form.State,
ErrorDescription: "cannot create grant for user",
ErrorCode: ErrorCodeServerError,
}, form.RedirectURI)
return
}
if len(form.Nonce) > 0 {
err := grant.SetNonce(form.Nonce)
if err != nil {
log.Error("Unable to update nonce: %v", err)
}
}
var codeChallenge, codeChallengeMethod string
codeChallenge, _ = ctx.Session.Get("CodeChallenge").(string)
codeChallengeMethod, _ = ctx.Session.Get("CodeChallengeMethod").(string)
code, err := grant.GenerateNewAuthorizationCode(form.RedirectURI, codeChallenge, codeChallengeMethod)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
return
}
redirect, err := code.GenerateRedirectURI(form.State)
if err != nil {
handleServerError(ctx, form.State, form.RedirectURI)
return
}
ctx.Redirect(redirect.String(), 302)
}
// AccessTokenOAuth manages all access token requests by the client
func AccessTokenOAuth(ctx *context.Context, form auth.AccessTokenForm) {
if form.ClientID == "" {
authHeader := ctx.Req.Header.Get("Authorization")
authContent := strings.SplitN(authHeader, " ", 2)
if len(authContent) == 2 && authContent[0] == "Basic" {
payload, err := base64.StdEncoding.DecodeString(authContent[1])
if err != nil {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot parse basic auth header",
})
return
}
pair := strings.SplitN(string(payload), ":", 2)
if len(pair) != 2 {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot parse basic auth header",
})
return
}
form.ClientID = pair[0]
form.ClientSecret = pair[1]
}
}
switch form.GrantType {
case "refresh_token":
handleRefreshToken(ctx, form)
return
case "authorization_code":
handleAuthorizationCode(ctx, form)
return
default:
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnsupportedGrantType,
ErrorDescription: "Only refresh_token or authorization_code grant type is supported",
})
}
}
func handleRefreshToken(ctx *context.Context, form auth.AccessTokenForm) {
token, err := models.ParseOAuth2Token(form.RefreshToken)
if err != nil {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnauthorizedClient,
ErrorDescription: "client is not authorized",
})
return
}
// get grant before increasing counter
grant, err := models.GetOAuth2GrantByID(token.GrantID)
if err != nil || grant == nil {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidGrant,
ErrorDescription: "grant does not exist",
})
return
}
// check if token got already used
if setting.OAuth2.InvalidateRefreshTokens && (grant.Counter != token.Counter || token.Counter == 0) {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnauthorizedClient,
ErrorDescription: "token was already used",
})
log.Warn("A client tried to use a refresh token for grant_id = %d was used twice!", grant.ID)
return
}
accessToken, tokenErr := newAccessTokenResponse(grant, form.ClientSecret)
if tokenErr != nil {
handleAccessTokenError(ctx, *tokenErr)
return
}
ctx.JSON(200, accessToken)
}
func handleAuthorizationCode(ctx *context.Context, form auth.AccessTokenForm) {
app, err := models.GetOAuth2ApplicationByClientID(form.ClientID)
if err != nil {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidClient,
ErrorDescription: fmt.Sprintf("cannot load client with client id: '%s'", form.ClientID),
})
return
}
if !app.ValidateClientSecret([]byte(form.ClientSecret)) {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnauthorizedClient,
ErrorDescription: "client is not authorized",
})
return
}
if form.RedirectURI != "" && !app.ContainsRedirectURI(form.RedirectURI) {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnauthorizedClient,
ErrorDescription: "client is not authorized",
})
return
}
authorizationCode, err := models.GetOAuth2AuthorizationByCode(form.Code)
if err != nil || authorizationCode == nil {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnauthorizedClient,
ErrorDescription: "client is not authorized",
})
return
}
// check if code verifier authorizes the client, PKCE support
if !authorizationCode.ValidateCodeChallenge(form.CodeVerifier) {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeUnauthorizedClient,
ErrorDescription: "client is not authorized",
})
return
}
// check if granted for this application
if authorizationCode.Grant.ApplicationID != app.ID {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidGrant,
ErrorDescription: "invalid grant",
})
return
}
// remove token from database to deny duplicate usage
if err := authorizationCode.Invalidate(); err != nil {
handleAccessTokenError(ctx, AccessTokenError{
ErrorCode: AccessTokenErrorCodeInvalidRequest,
ErrorDescription: "cannot proceed your request",
})
}
resp, tokenErr := newAccessTokenResponse(authorizationCode.Grant, form.ClientSecret)
if tokenErr != nil {
handleAccessTokenError(ctx, *tokenErr)
return
}
// send successful response
ctx.JSON(200, resp)
}
func handleAccessTokenError(ctx *context.Context, acErr AccessTokenError) {
ctx.JSON(400, acErr)
}
func handleServerError(ctx *context.Context, state string, redirectURI string) {
handleAuthorizeError(ctx, AuthorizeError{
ErrorCode: ErrorCodeServerError,
ErrorDescription: "A server error occurred",
State: state,
}, redirectURI)
}
func handleAuthorizeError(ctx *context.Context, authErr AuthorizeError, redirectURI string) {
if redirectURI == "" {
log.Warn("Authorization failed: %v", authErr.ErrorDescription)
ctx.Data["Error"] = authErr
ctx.HTML(400, tplGrantError)
return
}
redirect, err := url.Parse(redirectURI)
if err != nil {
ctx.ServerError("url.Parse", err)
return
}
q := redirect.Query()
q.Set("error", string(authErr.ErrorCode))
q.Set("error_description", authErr.ErrorDescription)
q.Set("state", authErr.State)
redirect.RawQuery = q.Encode()
ctx.Redirect(redirect.String(), 302)
}