upstream: allow UpdateKnownHosts=yes to function when multiple

known_hosts files are in use. When updating host keys, ssh will now search
subsequent known_hosts files, but will add new/changed host keys to the first
specified file only. bz#2738

ok markus@

OpenBSD-Commit-ID: 6ded6d878a03e57d5aa20bab9c31f92e929dbc6c

1 files changed, 43 insertions, 14 deletions

diff --git a/clientloop.c b/clientloop.c
index d4c23d554..874e1286d 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.332 2020/01/23 07:10:22 dtucker Exp $ */
+/* $OpenBSD: clientloop.c,v 1.333 2020/01/25 00:21:08 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1895,6 +1895,7 @@ update_known_hosts(struct hostkeys_update_ctx *ctx)
             SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
         char *fp, *response;
         size_t i;
+        struct stat sb;
 
         for (i = 0; i < ctx->nkeys; i++) {
                 if (ctx->keys_seen[i] != 2)
@@ -1941,19 +1942,37 @@ update_known_hosts(struct hostkeys_update_ctx *ctx)
                 if (was_raw)
                         enter_raw_mode(1);
         }
-
+        if (options.update_hostkeys == 0)
+                return;
         /*
          * Now that all the keys are verified, we can go ahead and replace
          * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
          * cancel the operation).
          */
-        if (options.update_hostkeys != 0 &&
-            (r = hostfile_replace_entries(options.user_hostfiles[0],
-            ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys,
-            options.hash_known_hosts, 0,
-            options.fingerprint_hash)) != 0)
-                error("%s: hostfile_replace_entries failed: %s",
-                    __func__, ssh_err(r));
+        for (i = 0; i < options.num_user_hostfiles; i++) {
+                /*
+                 * NB. keys are only added to hostfiles[0], for the rest we
+                 * just delete the hostname entries.
+                 */
+                if (stat(options.user_hostfiles[i], &sb) != 0) {
+                        if (errno == ENOENT) {
+                                debug("%s: known hosts file %s does not exist",
+                                    __func__, strerror(errno));
+                        } else {
+                                error("%s: known hosts file %s inaccessible",
+                                    __func__, strerror(errno));
+                        }
+                        continue;
+                }
+                if ((r = hostfile_replace_entries(options.user_hostfiles[i],
+                    ctx->host_str, ctx->ip_str,
+                    i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0,
+                    options.hash_known_hosts, 0,
+                    options.fingerprint_hash)) != 0) {
+                        error("%s: hostfile_replace_entries failed for %s: %s",
+                            __func__, options.user_hostfiles[i], ssh_err(r));
+                }
+        }
 }
 
 static void
@@ -2146,11 +2165,21 @@ client_input_hostkeys(struct ssh *ssh)
             options.check_host_ip ? &ctx->ip_str : NULL);
 
         /* Find which keys we already know about. */
-        if ((r = hostkeys_foreach(options.user_hostfiles[0], hostkeys_find,
-            ctx, ctx->host_str, ctx->ip_str,
-            HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) {
-                error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r));
-                goto out;
+        for (i = 0; i < options.num_user_hostfiles; i++) {
+                debug("%s: searching %s for %s / %s", __func__,
+                    options.user_hostfiles[i], ctx->host_str, ctx->ip_str);
+                if ((r = hostkeys_foreach(options.user_hostfiles[i],
+                    hostkeys_find, ctx, ctx->host_str, ctx->ip_str,
+                    HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) {
+                        if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
+                                error("%s: hostkeys file %s does not exist",
+                                    __func__, options.user_hostfiles[i]);
+                                continue;
+                        }
+                        error("%s: hostkeys_foreach failed for %s: %s",
+                            __func__, options.user_hostfiles[i], ssh_err(r));
+                        goto out;
+                }
         }
 
         /* Figure out if we have any new keys to add */