- djm@cvs.openbsd.org 2014/07/03 22:23:46

     [sshconnect.c]
     when rekeying, skip file/DNS lookup if it is the same as the key sent
     during initial key exchange. bz#2154 patch from Iain Morgan; ok markus@

1 files changed, 19 insertions, 4 deletions

diff --git a/sshconnect.c b/sshconnect.c
index 590dfe0f7..799c8d00c 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.249 2014/06/24 01:13:21 djm Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.250 2014/07/03 22:23:46 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -65,6 +65,7 @@
 
 char *client_version_string = NULL;
 char *server_version_string = NULL;
+Key *previous_host_key = NULL;
 
 static int matching_host_key_dns = 0;
 
@@ -1217,7 +1218,7 @@ fail:
 int
 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
 {
-        int flags = 0;
+        int r = -1, flags = 0;
         char *fp;
         Key *plain = NULL;
 
@@ -1225,6 +1226,11 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
         debug("Server host key: %s %s", key_type(host_key), fp);
         free(fp);
 
+        if (key_equal(previous_host_key, host_key)) {
+                debug("%s: server host key matches cached key", __func__);
+                return 0;
+        }
+
         if (options.verify_host_key_dns) {
                 /*
                  * XXX certs are not yet supported for DNS, so downgrade
@@ -1239,7 +1245,8 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
                                     flags & DNS_VERIFY_MATCH &&
                                     flags & DNS_VERIFY_SECURE) {
                                         key_free(plain);
-                                        return 0;
+                                        r = 0;
+                                        goto done;
                                 }
                                 if (flags & DNS_VERIFY_MATCH) {
                                         matching_host_key_dns = 1;
@@ -1254,9 +1261,17 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
                 key_free(plain);
         }
 
-        return check_host_key(host, hostaddr, options.port, host_key, RDRW,
+        r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
             options.user_hostfiles, options.num_user_hostfiles,
             options.system_hostfiles, options.num_system_hostfiles);
+
+done:
+        if (r == 0 && host_key != NULL) {
+                key_free(previous_host_key);
+                previous_host_key = key_from_private(host_key);
+        }
+
+        return r;
 }
 
 /*