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@

diff --git a/usr.bin/ssh/auth2.c b/usr.bin/ssh/auth2.c
index 1cebd3f..2d5dbcb 100644 (file)
--- a/usr.bin/ssh/auth2.c
+++ b/usr.bin/ssh/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.
  *
@@ -208,6 +208,7 @@ 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)
 {
@@ -233,6 +234,12 @@ 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;
@@ -317,7 +324,7 @@ 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);