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authentik/outpost/pkg/proxy/oauth.go

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2020-10-29 20:42:01 +00:00
package proxy
import (
"context"
"errors"
"fmt"
"net/http"
"net/url"
"strings"
sessionsapi "github.com/oauth2-proxy/oauth2-proxy/pkg/apis/sessions"
"github.com/oauth2-proxy/oauth2-proxy/pkg/encryption"
"github.com/oauth2-proxy/oauth2-proxy/pkg/ip"
)
// GetRedirectURI returns the redirectURL that the upstream OAuth Provider will
// redirect clients to once authenticated
func (p *OAuthProxy) GetRedirectURI(host string) string {
// default to the request Host if not set
if p.redirectURL.Host != "" {
return p.redirectURL.String()
}
u := *p.redirectURL
if u.Scheme == "" {
if p.CookieSecure {
u.Scheme = httpsScheme
} else {
u.Scheme = httpScheme
}
}
u.Host = host
return u.String()
}
func (p *OAuthProxy) redeemCode(ctx context.Context, host, code string) (s *sessionsapi.SessionState, err error) {
if code == "" {
return nil, errors.New("missing code")
}
redirectURI := p.GetRedirectURI(host)
s, err = p.provider.Redeem(ctx, redirectURI, code)
if err != nil {
return
}
if s.Email == "" {
s.Email, err = p.provider.GetEmailAddress(ctx, s)
}
if s.PreferredUsername == "" {
s.PreferredUsername, err = p.provider.GetPreferredUsername(ctx, s)
if err != nil && err.Error() == "not implemented" {
err = nil
}
}
if s.User == "" {
s.User, err = p.provider.GetUserName(ctx, s)
if err != nil && err.Error() == "not implemented" {
err = nil
}
}
return
}
// GetRedirect reads the query parameter to get the URL to redirect clients to
// once authenticated with the OAuthProxy
func (p *OAuthProxy) GetRedirect(req *http.Request) (redirect string, err error) {
err = req.ParseForm()
if err != nil {
return
}
redirect = req.Header.Get("X-Auth-Request-Redirect")
if req.Form.Get("rd") != "" {
redirect = req.Form.Get("rd")
}
if !p.IsValidRedirect(redirect) {
// Use RequestURI to preserve ?query
redirect = req.URL.RequestURI()
if strings.HasPrefix(redirect, p.ProxyPrefix) {
redirect = "/"
}
}
return
}
// IsValidRedirect checks whether the redirect URL is whitelisted
func (p *OAuthProxy) IsValidRedirect(redirect string) bool {
switch {
case redirect == "":
// The user didn't specify a redirect, should fallback to `/`
return false
case strings.HasPrefix(redirect, "/") && !strings.HasPrefix(redirect, "//") && !invalidRedirectRegex.MatchString(redirect):
return true
case strings.HasPrefix(redirect, "http://") || strings.HasPrefix(redirect, "https://"):
redirectURL, err := url.Parse(redirect)
if err != nil {
p.logger.Printf("Rejecting invalid redirect %q: scheme unsupported or missing", redirect)
return false
}
redirectHostname := redirectURL.Hostname()
for _, domain := range p.whitelistDomains {
domainHostname, domainPort := splitHostPort(strings.TrimLeft(domain, "."))
if domainHostname == "" {
continue
}
if (redirectHostname == domainHostname) || (strings.HasPrefix(domain, ".") && strings.HasSuffix(redirectHostname, domainHostname)) {
// the domain names match, now validate the ports
// if the whitelisted domain's port is '*', allow all ports
// if the whitelisted domain contains a specific port, only allow that port
// if the whitelisted domain doesn't contain a port at all, only allow empty redirect ports ie http and https
redirectPort := redirectURL.Port()
if (domainPort == "*") ||
(domainPort == redirectPort) ||
(domainPort == "" && redirectPort == "") {
return true
}
}
}
p.logger.Printf("Rejecting invalid redirect %q: domain / port not in whitelist", redirect)
return false
default:
p.logger.Printf("Rejecting invalid redirect %q: not an absolute or relative URL", redirect)
return false
}
}
// IsWhitelistedRequest is used to check if auth should be skipped for this request
func (p *OAuthProxy) IsWhitelistedRequest(req *http.Request) bool {
isPreflightRequestAllowed := p.skipAuthPreflight && req.Method == "OPTIONS"
return isPreflightRequestAllowed || p.IsWhitelistedPath(req.URL.Path)
}
// IsWhitelistedPath is used to check if the request path is allowed without auth
func (p *OAuthProxy) IsWhitelistedPath(path string) bool {
for _, u := range p.compiledRegex {
if u.MatchString(path) {
return true
}
}
return false
}
// OAuthStart starts the OAuth2 authentication flow
func (p *OAuthProxy) OAuthStart(rw http.ResponseWriter, req *http.Request) {
prepareNoCache(rw)
nonce, err := encryption.Nonce()
if err != nil {
p.logger.Errorf("Error obtaining nonce: %v", err)
p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", err.Error())
return
}
p.SetCSRFCookie(rw, req, nonce)
redirect, err := p.GetRedirect(req)
if err != nil {
p.logger.Errorf("Error obtaining redirect: %v", err)
p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", err.Error())
return
}
redirectURI := p.GetRedirectURI(req.Host)
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http.Redirect(rw, req, p.provider.GetLoginURL(redirectURI, fmt.Sprintf("%v:%v", nonce, redirect)), http.StatusFound)
}
// OAuthCallback is the OAuth2 authentication flow callback that finishes the
// OAuth2 authentication flow
func (p *OAuthProxy) OAuthCallback(rw http.ResponseWriter, req *http.Request) {
remoteAddr := ip.GetClientString(p.realClientIPParser, req, true)
// finish the oauth cycle
err := req.ParseForm()
if err != nil {
p.logger.Errorf("Error while parsing OAuth2 callback: %v", err)
p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", err.Error())
return
}
errorString := req.Form.Get("error")
if errorString != "" {
p.logger.Errorf("Error while parsing OAuth2 callback: %s", errorString)
p.ErrorPage(rw, http.StatusForbidden, "Permission Denied", errorString)
return
}
session, err := p.redeemCode(req.Context(), req.Host, req.Form.Get("code"))
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if err != nil {
p.logger.Errorf("Error redeeming code during OAuth2 callback: %v", err)
p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", "Internal Error")
return
}
s := strings.SplitN(req.Form.Get("state"), ":", 2)
if len(s) != 2 {
p.logger.Error("Error while parsing OAuth2 state: invalid length")
p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", "Invalid State")
return
}
nonce := s[0]
redirect := s[1]
c, err := req.Cookie(p.CSRFCookieName)
if err != nil {
p.logger.WithField("user", session.Email).WithField("status", "AuthFailure").Info("Invalid authentication via OAuth2: unable to obtain CSRF cookie")
p.ErrorPage(rw, http.StatusForbidden, "Permission Denied", err.Error())
return
}
p.ClearCSRFCookie(rw, req)
if c.Value != nonce {
p.logger.WithField("is", c.Value).WithField("should", nonce).WithField("user", session.Email).WithField("status", "AuthFailure").Info("Invalid authentication via OAuth2: CSRF token mismatch, potential attack")
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p.ErrorPage(rw, http.StatusForbidden, "Permission Denied", "CSRF Failed")
return
}
if !p.IsValidRedirect(redirect) {
redirect = "/"
}
// set cookie, or deny
if p.provider.ValidateGroup(session.Email) {
p.logger.WithField("user", session.Email).WithField("status", "AuthFailure").Infof("Authenticated via OAuth2: %s", session)
err := p.SaveSession(rw, req, session)
if err != nil {
p.logger.Printf("Error saving session state for %s: %v", remoteAddr, err)
p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", err.Error())
return
}
http.Redirect(rw, req, redirect, http.StatusFound)
} else {
p.logger.WithField("user", session.Email).WithField("status", "AuthFailure").Info("Invalid authentication via OAuth2: unauthorized")
p.ErrorPage(rw, http.StatusForbidden, "Permission Denied", "Invalid Account")
}
}