upstream: limit artificial login delay to a reasonable maximum (5s)

and don't delay at all for the "none" authentication mechanism. Patch by
Dmitry Belyavskiy in bz3602 with polish/ok dtucker@

OpenBSD-Commit-ID: 85b364676dd84cf1de0e98fc2fbdcb1a844ce515

diff --git a/auth2.c b/auth2.c
index 34346e5731dec56dd433cd308e3b42b48e974b2a..c628999e0bb62d574469329ce4b4c7abf9e7db4a 100644 (file)
--- a/auth2.c
+++ b/auth2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2.c,v 1.166 2023/03/08 04:43:12 guenther Exp $ */
+/* $OpenBSD: auth2.c,v 1.167 2023/08/28 09:48:11 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -218,6 +218,7 @@ input_service_request(int type, u_int32_t seq, struct ssh *ssh)
 }
 
 #define MIN_FAIL_DELAY_SECONDS 0.005
+#define MAX_FAIL_DELAY_SECONDS 5.0
 static double
 user_specific_delay(const char *user)
 {
@@ -243,6 +244,12 @@ ensure_minimum_time_since(double start, double seconds)
        struct timespec ts;
        double elapsed = monotime_double() - start, req = seconds, remain;
 
+       if (elapsed > MAX_FAIL_DELAY_SECONDS) {
+               debug3_f("elapsed %0.3lfms exceeded the max delay "
+                   "requested %0.3lfms)", elapsed*1000, req*1000);
+               return;
+       }
+
        /* if we've already passed the requested time, scale up */
        while ((remain = seconds - elapsed) < 0.0)
                seconds *= 2;
@@ -334,7 +341,7 @@ input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
                debug2("input_userauth_request: try method %s", method);
                authenticated = m->userauth(ssh, method);
        }
-       if (!authctxt->authenticated)
+       if (!authctxt->authenticated && strcmp(method, "none") != 0)
                ensure_minimum_time_since(tstart,
                    user_specific_delay(authctxt->user));
        userauth_finish(ssh, authenticated, method, NULL);