Attachment 2864 Details for Bug 2607 – use /proc/self/exe or environment variable to launch port forwarding for ProxyJump

[patch] use /proc/self/exe or environment variable to launch port forwarding for ProxyJump

0001-add-environment-variable-SSH_CUSTOM_CMD-for-ProxyJum.patch (text/plain), 3.00 KB, created by Stefan Tomanek on 2016-08-23 06:06:01 AEST

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Creator: Stefan Tomanek

Created: 2016-08-23 06:06:01 AEST

Size: 3.00 KB

patch

obsolete

>From 2795acae5b6191c7509878162897c177937ea5fa Mon Sep 17 00:00:00 2001
>From: Stefan Tomanek <stefan.tomanek@wertarbyte.de>
>Date: Sun, 21 Aug 2016 17:04:22 +0200
>Subject: [PATCH] add environment variable SSH_CUSTOM_CMD for ProxyJump
>
>This change makes the ProxyJump functionality read the environment variable
>SSH_CUSTOM_CMD to construct the proxy command line; this makes it possible to
>specify the path to a custom ssh binary as well as add extra flags. Even if the
>variable is unspecified or empty, the ssh binary used to establish the
>conection is not necessarily the one found first in $PATH; this patch uses the
>file /proc/self/exe available on many platforms to identify the binary of the
>already running process to launch a ProxyJump forwarding.
>
>If these two approaches fail, it falls back to the existing behaviour of just
>assuming "ssh" as command.
>---
> configure.ac |  8 ++++++++
> ssh.1        |  5 +++++
> ssh.c        | 17 ++++++++++++++++-
> 3 files changed, 29 insertions(+), 1 deletion(-)
>
>diff --git a/configure.ac b/configure.ac
>index a3c22c1..fbd54e8 100644
>--- a/configure.ac
>+++ b/configure.ac
>@@ -1448,6 +1448,14 @@ else
> 	AC_MSG_RESULT([no])
> fi
> 
>+AC_MSG_CHECKING([for /proc/self/exe link])
>+if test -L "/proc/self/exe" ; then
>+	AC_DEFINE([HAVE_PROC_SELF_EXE], [1], [Define if you have /proc/self/exe])
>+	AC_MSG_RESULT([yes])
>+else
>+	AC_MSG_RESULT([no])
>+fi
>+
> # Check whether user wants S/Key support
> SKEY_MSG="no"
> AC_ARG_WITH([skey],
>diff --git a/ssh.1 b/ssh.1
>index 4011c65..6fe1582 100644
>--- a/ssh.1
>+++ b/ssh.1
>@@ -330,6 +330,11 @@ Multiple jump hops may be specified separated by comma characters.
> This is a shortcut to specify a
> .Cm ProxyJump
> configuration directive.
>+When constructing the proxy command lines, the environment variable
>+.Ev SSH_CUSTOM_CMD
>+can be used to specify the
>+.Nm
>+binary to use.
> .Pp
> .It Fl K
> Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI
>diff --git a/ssh.c b/ssh.c
>index 03a23fb..c97f230 100644
>--- a/ssh.c
>+++ b/ssh.c
>@@ -1096,6 +1096,20 @@ main(int ac, char **av)
> 	 */
> 	if (options.jump_host != NULL) {
> 		char port_s[8];
>+#ifdef HAVE_PROC_SELF_EXE
>+		char ssh_path[PATH_MAX];
>+#endif
>+		char *ssh_cmd = getenv("SSH_CUSTOM_CMD");
>+		if (ssh_cmd && ssh_cmd[0] != '\0') {
>+			debug("Using custom SSH command: '%s'", ssh_cmd);
>+#ifdef HAVE_PROC_SELF_EXE
>+		} else if (readlink("/proc/self/exe", ssh_path, PATH_MAX) != -1) {
>+			debug("Located own ssh binary: '%s'", ssh_path);
>+			ssh_cmd = ssh_path;
>+#endif
>+		} else {
>+			ssh_cmd = "ssh";
>+		}
> 
> 		/* Consistency check */
> 		if (options.proxy_command != NULL)
>@@ -1104,7 +1118,8 @@ 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",
>+		    ssh_cmd,
> 		    /* Optional "-l user" argument if jump_user set */
> 		    options.jump_user == NULL ? "" : " -l ",
> 		    options.jump_user == NULL ? "" : options.jump_user,
>-- 
>2.1.4
>

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Attachments on bug 2607: 2864