upstream: add a SessionType directive to ssh_config, allowing the

configuration file to offer equivalent control to the -N (no session) and -s
(subsystem) command-line flags.

Part of GHPR#231 by Volker Diels-Grabsch with some minor tweaks;
feedback and ok dtucker@

OpenBSD-Commit-ID: 726ee931dd4c5cc7f1d7a187b26f41257f9a2d12

1 files changed, 21 insertions, 2 deletions

diff --git a/readconf.c b/readconf.c
index 3bec3a9fb..4b1cda2ee 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.358 2021/07/02 05:11:21 dtucker Exp $ */
+/* $OpenBSD: readconf.c,v 1.359 2021/07/13 23:48:36 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -167,7 +167,8 @@ typedef enum {
 	oTunnel, oTunnelDevice,
 	oLocalCommand, oPermitLocalCommand, oRemoteCommand,
 	oVisualHostKey,
-	oKexAlgorithms, oIPQoS, oRequestTTY, oIgnoreUnknown, oProxyUseFdpass,
+	oKexAlgorithms, oIPQoS, oRequestTTY, oSessionType,
+	oIgnoreUnknown, oProxyUseFdpass,
 	oCanonicalDomains, oCanonicalizeHostname, oCanonicalizeMaxDots,
 	oCanonicalizeFallbackLocal, oCanonicalizePermittedCNAMEs,
 	oStreamLocalBindMask, oStreamLocalBindUnlink, oRevokedHostKeys,
@@ -297,6 +298,7 @@ static struct {
 	{ "kexalgorithms", oKexAlgorithms },
 	{ "ipqos", oIPQoS },
 	{ "requesttty", oRequestTTY },
+	{ "sessiontype", oSessionType },
 	{ "proxyusefdpass", oProxyUseFdpass },
 	{ "canonicaldomains", oCanonicalDomains },
 	{ "canonicalizefallbacklocal", oCanonicalizeFallbackLocal },
@@ -872,6 +874,12 @@ static const struct multistate multistate_requesttty[] = {
 	{ "auto",			REQUEST_TTY_AUTO },
 	{ NULL, -1 }
 };
+static const struct multistate multistate_sessiontype[] = {
+	{ "none",			SESSION_TYPE_NONE },
+	{ "subsystem",			SESSION_TYPE_SUBSYSTEM },
+	{ "default",			SESSION_TYPE_DEFAULT },
+	{ NULL, -1 }
+};
 static const struct multistate multistate_canonicalizehostname[] = {
 	{ "true",			SSH_CANONICALISE_YES },
 	{ "false",			SSH_CANONICALISE_NO },
@@ -1941,6 +1949,11 @@ parse_pubkey_algos:
 		multistate_ptr = multistate_requesttty;
 		goto parse_multistate;
 
+	case oSessionType:
+		intptr = &options->session_type;
+		multistate_ptr = multistate_sessiontype;
+		goto parse_multistate;
+
 	case oIgnoreUnknown:
 		charptr = &options->ignored_unknown;
 		goto parse_string;
@@ -2363,6 +2376,7 @@ initialize_options(Options * options)
 	options->ip_qos_interactive = -1;
 	options->ip_qos_bulk = -1;
 	options->request_tty = -1;
+	options->session_type = -1;
 	options->proxy_use_fdpass = -1;
 	options->ignored_unknown = NULL;
 	options->num_canonical_domains = 0;
@@ -2549,6 +2563,8 @@ fill_default_options(Options * options)
 		options->ip_qos_bulk = IPTOS_DSCP_CS1;
 	if (options->request_tty == -1)
 		options->request_tty = REQUEST_TTY_AUTO;
+	if (options->session_type == -1)
+		options->session_type = SESSION_TYPE_DEFAULT;
 	if (options->proxy_use_fdpass == -1)
 		options->proxy_use_fdpass = 0;
 	if (options->canonicalize_max_dots == -1)
@@ -3063,6 +3079,8 @@ fmt_intarg(OpCodes code, int val)
 		return fmt_multistate_int(val, multistate_tunnel);
 	case oRequestTTY:
 		return fmt_multistate_int(val, multistate_requesttty);
+	case oSessionType:
+		return fmt_multistate_int(val, multistate_sessiontype);
 	case oCanonicalizeHostname:
 		return fmt_multistate_int(val, multistate_canonicalizehostname);
 	case oAddKeysToAgent:
@@ -3224,6 +3242,7 @@ dump_client_config(Options *o, const char *host)
 	dump_cfg_fmtint(oProxyUseFdpass, o->proxy_use_fdpass);
 	dump_cfg_fmtint(oPubkeyAuthentication, o->pubkey_authentication);
 	dump_cfg_fmtint(oRequestTTY, o->request_tty);
+	dump_cfg_fmtint(oSessionType, o->session_type);
 	dump_cfg_fmtint(oStreamLocalBindUnlink, o->fwd_opts.streamlocal_bind_unlink);
 	dump_cfg_fmtint(oStrictHostKeyChecking, o->strict_host_key_checking);
 	dump_cfg_fmtint(oTCPKeepAlive, o->tcp_keep_alive);