upstream: enable UpdateKnownHosts=yes if the configuration

specifies only the default known_hosts files, otherwise select
UpdateKnownHosts=ask; ok markus@

OpenBSD-Commit-ID: ab401a5ec4a33d2e1a9449eae6202e4b6d427df7

1 files changed, 14 insertions, 3 deletions

diff --git a/readconf.c b/readconf.c
index 36312d583..a6a160182 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.323 2020/01/25 00:22:31 djm Exp $ */
+/* $OpenBSD: readconf.c,v 1.324 2020/01/30 22:19:32 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2110,6 +2110,19 @@ fill_default_options(Options * options)
                 options->system_hostfiles[options->num_system_hostfiles++] =
                     xstrdup(_PATH_SSH_SYSTEM_HOSTFILE2);
         }
+        if (options->update_hostkeys == -1) {
+                /*
+                 * Enable UpdateHostKeys non-interactively if the user has
+                 * not overridden the default known_hosts selection, or has
+                 * overridden it with the default. Otherwise, prompt.
+                 */
+                if (options->num_user_hostfiles == 0 ||
+                    (options->num_user_hostfiles == 1 && strcmp(options->
+                    user_hostfiles[0], _PATH_SSH_USER_HOSTFILE) == 0))
+                        options->update_hostkeys = SSH_UPDATE_HOSTKEYS_YES;
+                else
+                        options->update_hostkeys = SSH_UPDATE_HOSTKEYS_ASK;
+        }
         if (options->num_user_hostfiles == 0) {
                 options->user_hostfiles[options->num_user_hostfiles++] =
                     xstrdup(_PATH_SSH_USER_HOSTFILE);
@@ -2170,8 +2183,6 @@ fill_default_options(Options * options)
                 options->canonicalize_hostname = SSH_CANONICALISE_NO;
         if (options->fingerprint_hash == -1)
                 options->fingerprint_hash = SSH_FP_HASH_DEFAULT;
-        if (options->update_hostkeys == -1)
-                options->update_hostkeys = SSH_UPDATE_HOSTKEYS_ASK;
 #ifdef ENABLE_SK_INTERNAL
         if (options->sk_provider == NULL)
                 options->sk_provider = xstrdup("internal");