make AllowTcpForwarding accept "local" and "remote" in addition to its

current "yes"/"no" to allow the server to specify whether just local or
remote TCP forwarding is enabled. ok markus@

7 files changed, 62 insertions, 26 deletions

diff --git a/usr.bin/ssh/auth-options.c b/usr.bin/ssh/auth-options.c
index c6116ec1c2e..d3a922842fb 100644
--- a/usr.bin/ssh/auth-options.c
+++ b/usr.bin/ssh/auth-options.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.c,v 1.56 2011/10/18 04:58:26 djm Exp $ */
+/* $OpenBSD: auth-options.c,v 1.57 2012/12/02 20:46:11 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -347,7 +347,7 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 				xfree(patterns);
 				goto bad_option;
 			}
-			if (options.allow_tcp_forwarding)
+			if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0)
 				channel_add_permitted_opens(host, port);
 			xfree(patterns);
 			goto next_option;
diff --git a/usr.bin/ssh/channels.c b/usr.bin/ssh/channels.c
index 635e4833cff..b277d5fd2ec 100644
--- a/usr.bin/ssh/channels.c
+++ b/usr.bin/ssh/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.318 2012/04/23 08:18:17 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.319 2012/12/02 20:46:11 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -3135,12 +3135,10 @@ channel_add_adm_permitted_opens(char *host, int port)
 void
 channel_disable_adm_local_opens(void)
 {
-	if (num_adm_permitted_opens == 0) {
-		permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
-		permitted_adm_opens[num_adm_permitted_opens].host_to_connect
-		   = NULL;
-		num_adm_permitted_opens = 1;
-	}
+	channel_clear_adm_permitted_opens();
+	permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
+	permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
+	num_adm_permitted_opens = 1;
 }
 
 void
diff --git a/usr.bin/ssh/servconf.c b/usr.bin/ssh/servconf.c
index 99197785ea3..4ecfc8d0b8d 100644
--- a/usr.bin/ssh/servconf.c
+++ b/usr.bin/ssh/servconf.c
@@ -1,5 +1,5 @@
 
-/* $OpenBSD: servconf.c,v 1.232 2012/11/04 11:09:15 djm Exp $ */
+/* $OpenBSD: servconf.c,v 1.233 2012/12/02 20:46:11 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -236,7 +236,7 @@ fill_default_server_options(ServerOptions *options)
 	if (options->compression == -1)
 		options->compression = COMP_DELAYED;
 	if (options->allow_tcp_forwarding == -1)
-		options->allow_tcp_forwarding = 1;
+		options->allow_tcp_forwarding = FORWARD_ALLOW;
 	if (options->allow_agent_forwarding == -1)
 		options->allow_agent_forwarding = 1;
 	if (options->gateway_ports == -1)
@@ -747,6 +747,14 @@ static const struct multistate multistate_privsep[] = {
 	{ "no",				PRIVSEP_OFF },
 	{ NULL, -1 }
 };
+static const struct multistate multistate_tcpfwd[] = {
+	{ "yes",			FORWARD_ALLOW },
+	{ "all",			FORWARD_ALLOW },
+	{ "no",				FORWARD_DENY },
+	{ "remote",			FORWARD_REMOTE },
+	{ "local",			FORWARD_LOCAL },
+	{ NULL, -1 }
+};
 
 int
 process_server_config_line(ServerOptions *options, char *line,
@@ -1098,7 +1106,8 @@ process_server_config_line(ServerOptions *options, char *line,
 
 	case sAllowTcpForwarding:
 		intptr = &options->allow_tcp_forwarding;
-		goto parse_flag;
+		multistate_ptr = multistate_tcpfwd;
+		goto parse_multistate;
 
 	case sAllowAgentForwarding:
 		intptr = &options->allow_agent_forwarding;
@@ -1378,7 +1387,6 @@ process_server_config_line(ServerOptions *options, char *line,
 		}
 		if (strcmp(arg, "none") == 0) {
 			if (*activep && n == -1) {
-				channel_clear_adm_permitted_opens();
 				options->num_permitted_opens = 1;
 				channel_disable_adm_local_opens();
 			}
@@ -1735,6 +1743,8 @@ fmt_intarg(ServerOpCodes code, int val)
 		return fmt_multistate_int(val, multistate_compression);
 	case sUsePrivilegeSeparation:
 		return fmt_multistate_int(val, multistate_privsep);
+	case sAllowTcpForwarding:
+		return fmt_multistate_int(val, multistate_tcpfwd);
 	case sProtocol:
 		switch (val) {
 		case SSH_PROTO_1:
diff --git a/usr.bin/ssh/servconf.h b/usr.bin/ssh/servconf.h
index da2374be289..48cf303fb06 100644
--- a/usr.bin/ssh/servconf.h
+++ b/usr.bin/ssh/servconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.h,v 1.105 2012/11/04 11:09:15 djm Exp $ */
+/* $OpenBSD: servconf.h,v 1.106 2012/12/02 20:46:11 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -42,6 +42,12 @@
 #define PRIVSEP_ON		1
 #define PRIVSEP_NOSANDBOX	2
 
+/* AllowTCPForwarding */
+#define FORWARD_DENY		0
+#define FORWARD_REMOTE		(1)
+#define FORWARD_LOCAL		(1<<1)
+#define FORWARD_ALLOW		(FORWARD_REMOTE|FORWARD_LOCAL)
+
 #define DEFAULT_AUTH_FAIL_MAX	6	/* Default for MaxAuthTries */
 #define DEFAULT_SESSIONS_MAX	10	/* Default for MaxSessions */
 
@@ -116,7 +122,7 @@ typedef struct {
 	int     permit_user_env;	/* If true, read ~/.ssh/environment */
 	int     use_login;	/* If true, login(1) is used */
 	int     compression;	/* If true, compression is allowed */
-	int	allow_tcp_forwarding;
+	int	allow_tcp_forwarding; /* One of FORWARD_* */
 	int	allow_agent_forwarding;
 	u_int num_allow_users;
 	char   *allow_users[MAX_ALLOW_USERS];
diff --git a/usr.bin/ssh/serverloop.c b/usr.bin/ssh/serverloop.c
index 2105cc818ff..c47d03dfd39 100644
--- a/usr.bin/ssh/serverloop.c
+++ b/usr.bin/ssh/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.162 2012/06/20 04:42:58 djm Exp $ */
+/* $OpenBSD: serverloop.c,v 1.163 2012/12/02 20:46:11 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -918,7 +918,7 @@ server_input_window_size(int type, u_int32_t seq, void *ctxt)
 static Channel *
 server_request_direct_tcpip(void)
 {
-	Channel *c;
+	Channel *c = NULL;
 	char *target, *originator;
 	u_short target_port, originator_port;
 
@@ -931,9 +931,16 @@ server_request_direct_tcpip(void)
 	debug("server_request_direct_tcpip: originator %s port %d, target %s "
 	    "port %d", originator, originator_port, target, target_port);
 
-	/* XXX check permission */
-	c = channel_connect_to(target, target_port,
-	    "direct-tcpip", "direct-tcpip");
+	/* XXX fine grained permissions */
+	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
+	    !no_port_forwarding_flag) {
+		c = channel_connect_to(target, target_port,
+		    "direct-tcpip", "direct-tcpip");
+	} else {
+		logit("refused local port forward: "
+		    "originator %s port %d, target %s port %d",
+		    originator, originator_port, target, target_port);
+	}
 
 	xfree(originator);
 	xfree(target);
@@ -1089,7 +1096,7 @@ server_input_global_request(int type, u_int32_t seq, void *ctxt)
 		    listen_address, listen_port);
 
 		/* check permissions */
-		if (!options.allow_tcp_forwarding ||
+		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
 		    no_port_forwarding_flag ||
 		    (!want_reply && listen_port == 0) ||
 		    (listen_port != 0 && listen_port < IPPORT_RESERVED &&
diff --git a/usr.bin/ssh/session.c b/usr.bin/ssh/session.c
index 2beb2430ab1..41bcd577bd3 100644
--- a/usr.bin/ssh/session.c
+++ b/usr.bin/ssh/session.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.260 2012/03/15 03:10:27 guenther Exp $ */
+/* $OpenBSD: session.c,v 1.261 2012/12/02 20:46:11 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -256,7 +256,10 @@ do_authenticated(Authctxt *authctxt)
 	setproctitle("%s", authctxt->pw->pw_name);
 
 	/* setup the channel layer */
-	if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
+	if (no_port_forwarding_flag ||
+	    (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0)
+		channel_disable_adm_local_opens();
+	else
 		channel_permit_all_opens();
 
 	auth_debug_send();
@@ -366,7 +369,7 @@ do_authenticated1(Authctxt *authctxt)
 				debug("Port forwarding not permitted for this authentication.");
 				break;
 			}
-			if (!options.allow_tcp_forwarding) {
+			if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) {
 				debug("Port forwarding not permitted.");
 				break;
 			}
diff --git a/usr.bin/ssh/sshd_config.5 b/usr.bin/ssh/sshd_config.5
index 91935d0291a..4d16bd35518 100644
--- a/usr.bin/ssh/sshd_config.5
+++ b/usr.bin/ssh/sshd_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: sshd_config.5,v 1.149 2012/11/04 11:09:15 djm Exp $
-.Dd $Mdocdate: November 4 2012 $
+.\" $OpenBSD: sshd_config.5,v 1.150 2012/12/02 20:46:11 djm Exp $
+.Dd $Mdocdate: December 2 2012 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -124,6 +124,18 @@ in
 for more information on patterns.
 .It Cm AllowTcpForwarding
 Specifies whether TCP forwarding is permitted.
+The available options are
+.Dq yes
+or
+.Dq all
+to allow TCP forwarding,
+.Dq no
+to prevent all TCP forwarding,
+.Dq local
+to allow local (from the perspective of
+.Xr ssh 1 ) forwarding only or
+.Dq remote
+to allow remote forwarding only.
 The default is
 .Dq yes .
 Note that disabling TCP forwarding does not improve security unless