- djm@cvs.openbsd.org 2011/09/09 22:46:44
[channels.c channels.h clientloop.h mux.c ssh.c]
support for cancelling local and remote port forwards via the multiplex
socket. Use ssh -O cancel -L xx:xx:xx -R yy:yy:yy user@host" to request
the cancellation of the specified forwardings; ok markus@
diff --git a/channels.c b/channels.c
index 24d4a9f..0f7e1a8 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.311 2011/06/22 22:08:42 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.312 2011/09/09 22:46:44 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -302,6 +302,8 @@
buffer_init(&c->output);
buffer_init(&c->extended);
c->path = NULL;
+ c->listening_addr = NULL;
+ c->listening_port = 0;
c->ostate = CHAN_OUTPUT_OPEN;
c->istate = CHAN_INPUT_OPEN;
c->flags = 0;
@@ -411,6 +413,10 @@
xfree(c->path);
c->path = NULL;
}
+ if (c->listening_addr) {
+ xfree(c->listening_addr);
+ c->listening_addr = NULL;
+ }
while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
if (cc->abandon_cb != NULL)
cc->abandon_cb(c, cc->ctx);
@@ -2634,6 +2640,46 @@
IPv4or6 = af;
}
+
+/*
+ * Determine whether or not a port forward listens to loopback, the
+ * specified address or wildcard. On the client, a specified bind
+ * address will always override gateway_ports. On the server, a
+ * gateway_ports of 1 (``yes'') will override the client's specification
+ * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
+ * will bind to whatever address the client asked for.
+ *
+ * Special-case listen_addrs are:
+ *
+ * "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
+ * "" (empty string), "*" -> wildcard v4/v6
+ * "localhost" -> loopback v4/v6
+ */
+static const char *
+channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
+ int is_client, int gateway_ports)
+{
+ const char *addr = NULL;
+ int wildcard = 0;
+
+ if (listen_addr == NULL) {
+ /* No address specified: default to gateway_ports setting */
+ if (gateway_ports)
+ wildcard = 1;
+ } else if (gateway_ports || is_client) {
+ if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
+ strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
+ *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
+ (!is_client && gateway_ports == 1))
+ wildcard = 1;
+ else if (strcmp(listen_addr, "localhost") != 0)
+ addr = listen_addr;
+ }
+ if (wildcardp != NULL)
+ *wildcardp = wildcard;
+ return addr;
+}
+
static int
channel_setup_fwd_listener(int type, const char *listen_addr,
u_short listen_port, int *allocated_listen_port,
@@ -2659,36 +2705,9 @@
return 0;
}
- /*
- * Determine whether or not a port forward listens to loopback,
- * specified address or wildcard. On the client, a specified bind
- * address will always override gateway_ports. On the server, a
- * gateway_ports of 1 (``yes'') will override the client's
- * specification and force a wildcard bind, whereas a value of 2
- * (``clientspecified'') will bind to whatever address the client
- * asked for.
- *
- * Special-case listen_addrs are:
- *
- * "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
- * "" (empty string), "*" -> wildcard v4/v6
- * "localhost" -> loopback v4/v6
- */
- addr = NULL;
- if (listen_addr == NULL) {
- /* No address specified: default to gateway_ports setting */
- if (gateway_ports)
- wildcard = 1;
- } else if (gateway_ports || is_client) {
- if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
- strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
- *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
- (!is_client && gateway_ports == 1))
- wildcard = 1;
- else if (strcmp(listen_addr, "localhost") != 0)
- addr = listen_addr;
- }
-
+ /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
+ addr = channel_fwd_bind_addr(listen_addr, &wildcard,
+ is_client, gateway_ports);
debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
type, wildcard, (addr == NULL) ? "NULL" : addr);
@@ -2793,6 +2812,7 @@
c->path = xstrdup(host);
c->host_port = port_to_connect;
c->listening_port = listen_port;
+ c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
success = 1;
}
if (success == 0)
@@ -2810,9 +2830,36 @@
for (i = 0; i < channels_alloc; i++) {
Channel *c = channels[i];
+ if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
+ continue;
+ if (strcmp(c->path, host) == 0 && c->listening_port == port) {
+ debug2("%s: close channel %d", __func__, i);
+ channel_free(c);
+ found = 1;
+ }
+ }
- if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
- strcmp(c->path, host) == 0 && c->listening_port == port) {
+ return (found);
+}
+
+int
+channel_cancel_lport_listener(const char *lhost, u_short lport,
+ u_short cport, int gateway_ports)
+{
+ u_int i;
+ int found = 0;
+ const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, gateway_ports);
+
+ for (i = 0; i < channels_alloc; i++) {
+ Channel *c = channels[i];
+ if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
+ continue;
+ if (c->listening_port != lport || c->host_port != cport)
+ continue;
+ if ((c->listening_addr == NULL && addr != NULL) ||
+ (c->listening_addr != NULL && addr == NULL))
+ continue;
+ if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
debug2("%s: close channel %d", __func__, i);
channel_free(c);
found = 1;
@@ -2843,10 +2890,30 @@
}
/*
+ * Translate the requested rfwd listen host to something usable for
+ * this server.
+ */
+static const char *
+channel_rfwd_bind_host(const char *listen_host)
+{
+ if (listen_host == NULL) {
+ if (datafellows & SSH_BUG_RFWD_ADDR)
+ return "127.0.0.1";
+ else
+ return "localhost";
+ } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
+ if (datafellows & SSH_BUG_RFWD_ADDR)
+ return "0.0.0.0";
+ else
+ return "";
+ } else
+ return listen_host;
+}
+
+/*
* Initiate forwarding of connections to port "port" on remote host through
* the secure channel to host:port from local side.
*/
-
int
channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
const char *host_to_connect, u_short port_to_connect)
@@ -2855,25 +2922,10 @@
/* Send the forward request to the remote side. */
if (compat20) {
- const char *address_to_bind;
- if (listen_host == NULL) {
- if (datafellows & SSH_BUG_RFWD_ADDR)
- address_to_bind = "127.0.0.1";
- else
- address_to_bind = "localhost";
- } else if (*listen_host == '\0' ||
- strcmp(listen_host, "*") == 0) {
- if (datafellows & SSH_BUG_RFWD_ADDR)
- address_to_bind = "0.0.0.0";
- else
- address_to_bind = "";
- } else
- address_to_bind = listen_host;
-
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("tcpip-forward");
- packet_put_char(1); /* boolean: want reply */
- packet_put_cstring(address_to_bind);
+ packet_put_char(1); /* boolean: want reply */
+ packet_put_cstring(channel_rfwd_bind_host(listen_host));
packet_put_int(listen_port);
packet_send();
packet_write_wait();
@@ -2917,13 +2969,13 @@
* Request cancellation of remote forwarding of connection host:port from
* local side.
*/
-void
+int
channel_request_rforward_cancel(const char *host, u_short port)
{
int i;
if (!compat20)
- return;
+ return -1;
for (i = 0; i < num_permitted_opens; i++) {
if (permitted_opens[i].host_to_connect != NULL &&
@@ -2932,12 +2984,12 @@
}
if (i >= num_permitted_opens) {
debug("%s: requested forward not found", __func__);
- return;
+ return -1;
}
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("cancel-tcpip-forward");
packet_put_char(0);
- packet_put_cstring(host == NULL ? "" : host);
+ packet_put_cstring(channel_rfwd_bind_host(host));
packet_put_int(port);
packet_send();
@@ -2945,6 +2997,8 @@
permitted_opens[i].port_to_connect = 0;
xfree(permitted_opens[i].host_to_connect);
permitted_opens[i].host_to_connect = NULL;
+
+ return 0;
}
/*