feat(lib): ensure that clients store cookies (#501)
* feat(lib): ensure that clients store cookies If a client is misconfigured and does not store cookies, then they can get into a proof of work death spiral with Anubis. This fixes the problem by setting a test cookie whenever the user gets hit with a challenge page. If the test cookie is not there at challenge pass time, then they are blocked. Administrators will also get a log message explaining that the user intentionally broke cookie support and that this behavior is not an Anubis bug. Additionally, this ensures that clients being shown a challenge support gzip-compressed responses by showing the challenge page at gzip level 1. This level is intentionally chosen in order to minimize system impacts. The ClearCookie function is made more generic to account for cookie names as an argument. A correlating SetCookie function was also added to make it easier to set cookies. * chore(lib): clean up test code Signed-off-by: Xe Iaso <me@xeiaso.net> --------- Signed-off-by: Xe Iaso <me@xeiaso.net>
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Xe Iaso
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11 changed files with 200 additions and 154 deletions
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@ -121,21 +121,21 @@ func (s *Server) maybeReverseProxy(w http.ResponseWriter, r *http.Request, httpS
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ckie, err := r.Cookie(s.cookieName)
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if err != nil {
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lg.Debug("cookie not found", "path", r.URL.Path)
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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s.RenderIndex(w, r, rule, httpStatusOnly)
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return
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}
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if err := ckie.Valid(); err != nil {
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lg.Debug("cookie is invalid", "err", err)
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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s.RenderIndex(w, r, rule, httpStatusOnly)
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return
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}
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if time.Now().After(ckie.Expires) && !ckie.Expires.IsZero() {
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lg.Debug("cookie expired", "path", r.URL.Path)
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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s.RenderIndex(w, r, rule, httpStatusOnly)
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return
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}
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@ -146,7 +146,7 @@ func (s *Server) maybeReverseProxy(w http.ResponseWriter, r *http.Request, httpS
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if err != nil || !token.Valid {
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lg.Debug("invalid token", "path", r.URL.Path, "err", err)
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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s.RenderIndex(w, r, rule, httpStatusOnly)
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return
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}
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@ -162,7 +162,7 @@ func (s *Server) checkRules(w http.ResponseWriter, r *http.Request, cr policy.Ch
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s.ServeHTTPNext(w, r)
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return true
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case config.RuleDeny:
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Info("explicit deny")
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if rule == nil {
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lg.Error("rule is nil, cannot calculate checksum")
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@ -181,7 +181,7 @@ func (s *Server) checkRules(w http.ResponseWriter, r *http.Request, cr policy.Ch
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s.RenderBench(w, r)
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return true
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default:
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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slog.Error("CONFIG ERROR: unknown rule", "rule", cr.Rule)
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s.respondWithError(w, r, "Internal Server Error: administrator has misconfigured Anubis. Please contact the administrator and ask them to look for the logs around \"maybeReverseProxy.Rules\"")
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return true
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@ -233,6 +233,8 @@ func (s *Server) MakeChallenge(w http.ResponseWriter, r *http.Request) {
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lg = lg.With("check_result", cr)
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challenge := s.challengeFor(r, rule.Challenge.Difficulty)
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s.SetCookie(w, anubis.TestCookieName, challenge, "")
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err = encoder.Encode(struct {
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Rules *config.ChallengeRules `json:"rules"`
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Challenge string `json:"challenge"`
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@ -265,14 +267,14 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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cr, rule, err := s.check(r)
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if err != nil {
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lg.Error("check failed", "err", err)
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s.respondWithError(w, r, "Internal Server Error: administrator has misconfigured Anubis. Please contact the administrator and ask them to look for the logs around \"passChallenge\".\"")
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s.respondWithError(w, r, "Internal Server Error: administrator has misconfigured Anubis. Please contact the administrator and ask them to look for the logs around \"passChallenge\".")
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return
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}
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lg = lg.With("check_result", cr)
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nonceStr := r.FormValue("nonce")
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if nonceStr == "" {
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Debug("no nonce")
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s.respondWithError(w, r, "missing nonce")
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return
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@ -280,7 +282,7 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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elapsedTimeStr := r.FormValue("elapsedTime")
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if elapsedTimeStr == "" {
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Debug("no elapsedTime")
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s.respondWithError(w, r, "missing elapsedTime")
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return
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@ -288,7 +290,7 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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elapsedTime, err := strconv.ParseFloat(elapsedTimeStr, 64)
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if err != nil {
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Debug("elapsedTime doesn't parse", "err", err)
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s.respondWithError(w, r, "invalid elapsedTime")
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return
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@ -310,11 +312,21 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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challenge := s.challengeFor(r, rule.Challenge.Difficulty)
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if _, err := r.Cookie(anubis.TestCookieName); err == http.ErrNoCookie {
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s.ClearCookie(w, s.cookieName)
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s.ClearCookie(w, anubis.TestCookieName)
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lg.Warn("user has cookies disabled, this is not an anubis bug")
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s.respondWithError(w, r, "Your browser is configured to disable cookies. Anubis requires cookies for the legitimate interest of making sure you are a valid client. Please enable cookies for this domain")
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return
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}
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s.ClearCookie(w, anubis.TestCookieName)
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nonce, err := strconv.Atoi(nonceStr)
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if err != nil {
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Debug("nonce doesn't parse", "err", err)
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s.respondWithError(w, r, "invalid nonce")
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s.respondWithError(w, r, "invalid response")
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return
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}
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@ -322,7 +334,7 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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calculated := internal.SHA256sum(calcString)
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if subtle.ConstantTimeCompare([]byte(response), []byte(calculated)) != 1 {
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Debug("hash does not match", "got", response, "want", calculated)
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s.respondWithStatus(w, r, "invalid response", http.StatusForbidden)
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failedValidations.Inc()
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@ -331,7 +343,7 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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// compare the leading zeroes
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if !strings.HasPrefix(response, strings.Repeat("0", rule.Challenge.Difficulty)) {
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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lg.Debug("difficulty check failed", "response", response, "difficulty", rule.Challenge.Difficulty)
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s.respondWithStatus(w, r, "invalid response", http.StatusForbidden)
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failedValidations.Inc()
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@ -355,20 +367,12 @@ func (s *Server) PassChallenge(w http.ResponseWriter, r *http.Request) {
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tokenString, err := token.SignedString(s.priv)
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if err != nil {
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lg.Error("failed to sign JWT", "err", err)
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s.ClearCookie(w)
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s.ClearCookie(w, s.cookieName)
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s.respondWithError(w, r, "failed to sign JWT")
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return
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}
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http.SetCookie(w, &http.Cookie{
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Name: s.cookieName,
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Value: tokenString,
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Expires: time.Now().Add(s.opts.CookieExpiration),
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SameSite: http.SameSiteLaxMode,
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Domain: s.opts.CookieDomain,
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Partitioned: s.opts.CookiePartitioned,
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Path: cookiePath,
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})
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s.SetCookie(w, s.cookieName, tokenString, cookiePath)
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challengesValidated.Inc()
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lg.Debug("challenge passed, redirecting to app")
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