upstream commit

Add RemoteCommand option to specify a command in the
ssh config file instead of giving it on the client's command line.  This
command will be executed on the remote host.  The feature allows to automate
tasks using ssh config. OK markus@

Upstream-ID: 5d982fc17adea373a9c68cae1021ce0a0904a5ee

readconf.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.276 2017/05/20 02:35:47 djm Exp $ */
+/* $OpenBSD: readconf.c,v 1.277 2017/05/30 18:58:37 bluhm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -163,7 +163,8 @@ typedef enum {
 	oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly,
 	oSendEnv, oControlPath, oControlMaster, oControlPersist,
 	oHashKnownHosts,
-	oTunnel, oTunnelDevice, oLocalCommand, oPermitLocalCommand,
+	oTunnel, oTunnelDevice,
+	oLocalCommand, oPermitLocalCommand, oRemoteCommand,
 	oVisualHostKey,
 	oKexAlgorithms, oIPQoS, oRequestTTY, oIgnoreUnknown, oProxyUseFdpass,
 	oCanonicalDomains, oCanonicalizeHostname, oCanonicalizeMaxDots,
@@ -284,6 +285,7 @@ static struct {
 	{ "tunneldevice", oTunnelDevice },
 	{ "localcommand", oLocalCommand },
 	{ "permitlocalcommand", oPermitLocalCommand },
+	{ "remotecommand", oRemoteCommand },
 	{ "visualhostkey", oVisualHostKey },
 	{ "kexalgorithms", oKexAlgorithms },
 	{ "ipqos", oIPQoS },
@@ -1440,6 +1442,10 @@ process_config_line_depth(Options *options, struct passwd *pw, const char *host,
 		intptr = &options->permit_local_command;
 		goto parse_flag;
 
+	case oRemoteCommand:
+		charptr = &options->remote_command;
+		goto parse_command;
+
 	case oVisualHostKey:
 		intptr = &options->visual_host_key;
 		goto parse_flag;
@@ -1828,6 +1834,7 @@ initialize_options(Options * options)
 	options->tun_remote = -1;
 	options->local_command = NULL;
 	options->permit_local_command = -1;
+	options->remote_command = NULL;
 	options->add_keys_to_agent = -1;
 	options->identity_agent = NULL;
 	options->visual_host_key = -1;
@@ -2032,6 +2039,7 @@ fill_default_options(Options * options)
 		} \
 	} while(0)
 	CLEAR_ON_NONE(options->local_command);
+	CLEAR_ON_NONE(options->remote_command);
 	CLEAR_ON_NONE(options->proxy_command);
 	CLEAR_ON_NONE(options->control_path);
 	CLEAR_ON_NONE(options->revoked_host_keys);
@@ -2509,6 +2517,7 @@ dump_client_config(Options *o, const char *host)
 	dump_cfg_string(oKbdInteractiveDevices, o->kbd_interactive_devices);
 	dump_cfg_string(oKexAlgorithms, o->kex_algorithms ? o->kex_algorithms : KEX_CLIENT_KEX);
 	dump_cfg_string(oLocalCommand, o->local_command);
+	dump_cfg_string(oRemoteCommand, o->remote_command);
 	dump_cfg_string(oLogLevel, log_level_name(o->log_level));
 	dump_cfg_string(oMacs, o->macs ? o->macs : KEX_CLIENT_MAC);
 #ifdef ENABLE_PKCS11

readconf.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.h,v 1.121 2017/04/30 23:18:22 djm Exp $ */
+/* $OpenBSD: readconf.h,v 1.122 2017/05/30 18:58:37 bluhm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -134,6 +134,7 @@ typedef struct {
 
 	char	*local_command;
 	int	permit_local_command;
+	char	*remote_command;
 	int	visual_host_key;
 
 	int	request_tty;

ssh.1

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh.1,v 1.381 2017/05/05 10:41:58 naddy Exp $
-.Dd $Mdocdate: May 5 2017 $
+.\" $OpenBSD: ssh.1,v 1.382 2017/05/30 18:58:37 bluhm Exp $
+.Dd $Mdocdate: May 30 2017 $
 .Dt SSH 1
 .Os
 .Sh NAME
@@ -518,6 +518,7 @@ For full details of the options listed below, and their possible values, see
 .It PubkeyAcceptedKeyTypes
 .It PubkeyAuthentication
 .It RekeyLimit
+.It RemoteCommand
 .It RemoteForward
 .It RequestTTY
 .It SendEnv

ssh.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.460 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: ssh.c,v 1.461 2017/05/30 18:58:37 bluhm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -973,12 +973,6 @@ main(int ac, char **av)
 		}
 	}
 
-	/* Cannot fork to background if no command. */
-	if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
-	    !no_shell_flag)
-		fatal("Cannot fork into background without a command "
-		    "to execute.");
-
 	/*
 	 * Initialize "log" output.  Since we are the client all output
 	 * goes to stderr unless otherwise specified by -y or -E.
@@ -1133,6 +1127,15 @@ main(int ac, char **av)
 		options.use_privileged_port = 0;
 #endif
 
+	if (buffer_len(&command) != 0 && options.remote_command != NULL)
+		fatal("Cannot execute command-line and remote command.");
+
+	/* Cannot fork to background if no command. */
+	if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
+	    options.remote_command == NULL && !no_shell_flag)
+		fatal("Cannot fork into background without a command "
+		    "to execute.");
+
 	/* reinit */
 	log_init(argv0, options.log_level, options.log_facility, !use_syslog);
 
@@ -1141,7 +1144,7 @@ main(int ac, char **av)
 		tty_flag = 1;
 
 	/* Allocate a tty by default if no command specified. */
-	if (buffer_len(&command) == 0)
+	if (buffer_len(&command) == 0 && options.remote_command == NULL)
 		tty_flag = options.request_tty != REQUEST_TTY_NO;
 
 	/* Force no tty */
@@ -1197,6 +1200,27 @@ main(int ac, char **av)
 		free(cp);
 	}
 
+	if (options.remote_command != NULL) {
+		debug3("expanding RemoteCommand: %s", options.remote_command);
+		cp = options.remote_command;
+		options.remote_command = percent_expand(cp,
+		    "C", conn_hash_hex,
+		    "L", shorthost,
+		    "d", pw->pw_dir,
+		    "h", host,
+		    "l", thishost,
+		    "n", host_arg,
+		    "p", portstr,
+		    "r", options.user,
+		    "u", pw->pw_name,
+		    (char *)NULL);
+		debug3("expanded RemoteCommand: %s", options.remote_command);
+		free(cp);
+		buffer_append(&command, options.remote_command,
+		    strlen(options.remote_command));
+
+	}
+
 	if (options.control_path != NULL) {
 		cp = tilde_expand_filename(options.control_path,
 		    original_real_uid);

ssh_config.5

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh_config.5,v 1.248 2017/05/07 23:12:57 djm Exp $
-.Dd $Mdocdate: May 7 2017 $
+.\" $OpenBSD: ssh_config.5,v 1.249 2017/05/30 18:58:37 bluhm Exp $
+.Dd $Mdocdate: May 30 2017 $
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
@@ -1287,6 +1287,14 @@ is
 .Cm default none ,
 which means that rekeying is performed after the cipher's default amount
 of data has been sent or received and no time based rekeying is done.
+.It Cm RemoteCommand
+Specifies a command to execute on the remote machine after successfully
+connecting to the server.
+The command string extends to the end of the line, and is executed with
+the user's shell.
+The same escape character substitutions as for
+.Cm LocalCommand
+will be performed.
 .It Cm RemoteForward
 Specifies that a TCP port on the remote machine be forwarded over
 the secure channel to the specified host and port from the local machine.