From 36e9ce6b82afa2f0f5fe89f5b1707291e27f1342 Mon Sep 17 00:00:00 2001
From: djm <djm@openbsd.org>
Date: Mon, 28 Aug 2023 09:48:11 +0000
Subject: [PATCH] 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@

---
 usr.bin/ssh/auth2.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/usr.bin/ssh/auth2.c b/usr.bin/ssh/auth2.c
index 1cebd3f2dfd..2d5dbcb5bdb 100644
--- 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);
-- 
2.20.1