upstream: prefer argv0 to "ssh" when re-executing ssh for ProxyJump

directive; bz2831, feedback and ok dtucker@

OpenBSD-Commit-ID: 3cec709a131499fbb0c1ea8a0a9e0b0915ce769e

1 files changed, 11 insertions, 2 deletions

diff --git a/ssh.c b/ssh.c
index ce16627db..40e63c325 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.477 2018/04/14 21:50:41 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.478 2018/06/01 03:11:49 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1171,6 +1171,14 @@ main(int ac, char **av)
          */
         if (options.jump_host != NULL) {
                 char port_s[8];
+                const char *sshbin = argv0;
+
+                /*
+                 * Try to use SSH indicated by argv[0], but fall back to
+                 * "ssh" if it appears unavailable.
+                 */
+                if (strchr(argv0, '/') != NULL && access(argv0, X_OK) != 0)
+                        sshbin = "ssh";
 
                 /* Consistency check */
                 if (options.proxy_command != NULL)
@@ -1179,7 +1187,8 @@ main(int ac, char **av)
                 options.proxy_use_fdpass = 0;
                 snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
                 xasprintf(&options.proxy_command,
-                    "ssh%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
+                    "%s%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
+                    sshbin,
                     /* Optional "-l user" argument if jump_user set */
                     options.jump_user == NULL ? "" : " -l ",
                     options.jump_user == NULL ? "" : options.jump_user,