upstream: Add TOKEN percent expansion to LocalFoward and RemoteForward

when used for Unix domain socket forwarding.  Factor out the code for the
config keywords that use the most common subset of TOKENS into its own
function. bz#3014, ok jmc@ (man page bits) djm@

OpenBSD-Commit-ID: bffc9f7e7b5cf420309a057408bef55171fd0b97

2 files changed, 109 insertions, 59 deletions

diff --git a/ssh.c b/ssh.c
index 17608564..98b6ce78 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.526 2020/04/03 06:07:57 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.527 2020/04/10 00:52:07 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -176,13 +176,6 @@ char *forward_agent_sock_path = NULL;
 /* Various strings used to to percent_expand() arguments */
 static char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 static char uidstr[32], *host_arg, *conn_hash_hex;
-#define DEFAULT_CLIENT_PERCENT_EXPAND_ARGS \
-    "C", conn_hash_hex, \
-    "L", shorthost, \
-    "i", uidstr, \
-    "l", thishost, \
-    "n", host_arg, \
-    "p", portstr
 
 /* socket address the host resolves to */
 struct sockaddr_storage hostaddr;
@@ -238,6 +231,34 @@ tilde_expand_paths(char **paths, u_int num_paths)
 	}
 }
 
+#define DEFAULT_CLIENT_PERCENT_EXPAND_ARGS \
+    "C", conn_hash_hex, \
+    "L", shorthost, \
+    "i", uidstr, \
+    "l", thishost, \
+    "n", host_arg, \
+    "p", portstr
+
+/*
+ * Expands the set of percent_expand options used by the majority of keywords
+ * in the client that support percent expansion.
+ * Caller must free returned string.
+ */
+static char *
+default_client_percent_expand(const char *str, const char *homedir,
+    const char *remhost, const char *remuser, const char *locuser)
+{
+	return percent_expand(str,
+	    /* values from statics above */
+	    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
+	    /* values from arguments */
+	    "d", homedir,
+	    "h", remhost,
+	    "r", remuser,
+	    "u", locuser,
+	    (char *)NULL);
+}
+
 /*
  * Attempt to resolve a host name / port to a set of addresses and
  * optionally return any CNAMEs encountered along the way.
@@ -1345,13 +1366,8 @@ main(int ac, char **av)
 	if (options.remote_command != NULL) {
 		debug3("expanding RemoteCommand: %s", options.remote_command);
 		cp = options.remote_command;
-		options.remote_command = percent_expand(cp,
-		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
-		    "d", pw->pw_dir,
-		    "h", host,
-		    "r", options.user,
-		    "u", pw->pw_name,
-		    (char *)NULL);
+		options.remote_command = default_client_percent_expand(cp,
+		    pw->pw_dir, host, options.user, pw->pw_name);
 		debug3("expanded RemoteCommand: %s", options.remote_command);
 		free(cp);
 		if ((r = sshbuf_put(command, options.remote_command,
@@ -1362,25 +1378,15 @@ main(int ac, char **av)
 	if (options.control_path != NULL) {
 		cp = tilde_expand_filename(options.control_path, getuid());
 		free(options.control_path);
-		options.control_path = percent_expand(cp,
-		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
-		    "d", pw->pw_dir,
-		    "h", host,
-		    "r", options.user,
-		    "u", pw->pw_name,
-		    (char *)NULL);
+		options.control_path = default_client_percent_expand(cp,
+		    pw->pw_dir, host, options.user, pw->pw_name);
 		free(cp);
 	}
 
 	if (options.identity_agent != NULL) {
 		p = tilde_expand_filename(options.identity_agent, getuid());
-		cp = percent_expand(p,
-		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
-		    "d", pw->pw_dir,
-		    "h", host,
-		    "r", options.user,
-		    "u", pw->pw_name,
-		    (char *)NULL);
+		cp = default_client_percent_expand(p,
+		    pw->pw_dir, host, options.user, pw->pw_name);
 		free(p);
 		free(options.identity_agent);
 		options.identity_agent = cp;
@@ -1389,18 +1395,59 @@ main(int ac, char **av)
 	if (options.forward_agent_sock_path != NULL) {
 		p = tilde_expand_filename(options.forward_agent_sock_path,
 		    getuid());
-		cp = percent_expand(p,
-		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
-		    "d", pw->pw_dir,
-		    "h", host,
-		    "r", options.user,
-		    "u", pw->pw_name,
-		    (char *)NULL);
+		cp = default_client_percent_expand(p,
+		    pw->pw_dir, host, options.user, pw->pw_name);
 		free(p);
 		free(options.forward_agent_sock_path);
 		options.forward_agent_sock_path = cp;
 	}
 
+	for (i = 0; i < options.num_local_forwards; i++) {
+		if (options.local_forwards[i].listen_path != NULL) {
+			cp = options.local_forwards[i].listen_path;
+			p = options.local_forwards[i].listen_path =
+			    default_client_percent_expand(cp,
+			    pw->pw_dir, host, options.user, pw->pw_name);
+			if (strcmp(cp, p) != 0)
+				debug3("expanded LocalForward listen path "
+				    "'%s' -> '%s'", cp, p);
+			free(cp);
+		}
+		if (options.local_forwards[i].connect_path != NULL) {
+			cp = options.local_forwards[i].connect_path;
+			p = options.local_forwards[i].connect_path =
+			    default_client_percent_expand(cp,
+			    pw->pw_dir, host, options.user, pw->pw_name);
+			if (strcmp(cp, p) != 0)
+				debug3("expanded LocalForward connect path "
+				    "'%s' -> '%s'", cp, p);
+			free(cp);
+		}
+	}
+
+	for (i = 0; i < options.num_remote_forwards; i++) {
+		if (options.remote_forwards[i].listen_path != NULL) {
+			cp = options.remote_forwards[i].listen_path;
+			p = options.remote_forwards[i].listen_path =
+			    default_client_percent_expand(cp,
+			    pw->pw_dir, host, options.user, pw->pw_name);
+			if (strcmp(cp, p) != 0)
+				debug3("expanded RemoteForward listen path "
+				    "'%s' -> '%s'", cp, p);
+			free(cp);
+		}
+		if (options.remote_forwards[i].connect_path != NULL) {
+			cp = options.remote_forwards[i].connect_path;
+			p = options.remote_forwards[i].connect_path =
+			    default_client_percent_expand(cp,
+			    pw->pw_dir, host, options.user, pw->pw_name);
+			if (strcmp(cp, p) != 0)
+				debug3("expanded RemoteForward connect path "
+				    "'%s' -> '%s'", cp, p);
+			free(cp);
+		}
+	}
+
 	if (config_test) {
 		dump_client_config(&options, host);
 		exit(0);
@@ -2154,13 +2201,8 @@ load_public_identity_files(struct passwd *pw)
 			continue;
 		}
 		cp = tilde_expand_filename(options.identity_files[i], getuid());
-		filename = percent_expand(cp,
-		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
-		    "d", pw->pw_dir,
-		    "h", host,
-		    "r", options.user,
-		    "u", pw->pw_name,
-		    (char *)NULL);
+		filename = default_client_percent_expand(cp,
+		    pw->pw_dir, host, options.user, pw->pw_name);
 		free(cp);
 		check_load(sshkey_load_public(filename, &public, NULL),
 		    filename, "pubkey");
@@ -2209,13 +2251,8 @@ load_public_identity_files(struct passwd *pw)
 	for (i = 0; i < options.num_certificate_files; i++) {
 		cp = tilde_expand_filename(options.certificate_files[i],
 		    getuid());
-		filename = percent_expand(cp,
-		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS,
-		    "d", pw->pw_dir,
-		    "h", host,
-		    "r", options.user,
-		    "u", pw->pw_name,
-		    (char *)NULL);
+		filename = default_client_percent_expand(cp,
+		    pw->pw_dir, host, options.user, pw->pw_name);
 		free(cp);
 
 		check_load(sshkey_load_public(filename, &public, NULL),
diff --git a/ssh_config.5 b/ssh_config.5
index 9d89c13a..7bbc76aa 100644
--- a/ssh_config.5
+++ b/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 1.323 2020/04/03 02:27:12 dtucker Exp $
-.Dd $Mdocdate: April 3 2020 $
+.\" $OpenBSD: ssh_config.5,v 1.324 2020/04/10 00:52:07 dtucker Exp $
+.Dd $Mdocdate: April 10 2020 $
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
@@ -1125,12 +1125,15 @@ has been enabled.
 .It Cm LocalForward
 Specifies that a TCP port on the local machine be forwarded over
 the secure channel to the specified host and port from the remote machine.
-The first argument must be
+The first argument specifies the listener and may be
 .Sm off
 .Oo Ar bind_address : Oc Ar port
 .Sm on
-and the second argument must be
-.Ar host : Ns Ar hostport .
+or a Unix domain socket path.
+The second argument is the destination and may be
+.Ar host : Ns Ar hostport
+or a Unix domain socket path if the remote host supports it.
+.Pp
 IPv6 addresses can be specified by enclosing addresses in square brackets.
 Multiple forwardings may be specified, and additional forwardings can be
 given on the command line.
@@ -1149,6 +1152,9 @@ indicates that the listening port be bound for local use only, while an
 empty address or
 .Sq *
 indicates that the port should be available from all interfaces.
+Unix domain socket paths accept the tokens described in the
+.Sx TOKENS
+section.
 .It Cm LogLevel
 Gives the verbosity level that is used when logging messages from
 .Xr ssh 1 .
@@ -1401,12 +1407,14 @@ the secure channel.
 The remote port may either be forwarded to a specified host and port
 from the local machine, or may act as a SOCKS 4/5 proxy that allows a remote
 client to connect to arbitrary destinations from the local machine.
-The first argument must be
+The first argument is the listening specification and may be
 .Sm off
 .Oo Ar bind_address : Oc Ar port
 .Sm on
+or, if the remote host supports it, a Unix domain socket path.
 If forwarding to a specific destination then the second argument must be
-.Ar host : Ns Ar hostport ,
+.Ar host : Ns Ar hostport
+or a Unix domain socket path,
 otherwise if no destination argument is specified then the remote forwarding
 will be established as a SOCKS proxy.
 .Pp
@@ -1415,6 +1423,9 @@ Multiple forwardings may be specified, and additional
 forwardings can be given on the command line.
 Privileged ports can be forwarded only when
 logging in as root on the remote machine.
+Unix domain socket paths accept the tokens described in the
+.Sx TOKENS
+section.
 .Pp
 If the
 .Ar port
@@ -1845,13 +1856,15 @@ otherwise.
 The local username.
 .El
 .Pp
-.Cm Match exec ,
 .Cm CertificateFile ,
 .Cm ControlPath ,
 .Cm IdentityAgent ,
 .Cm IdentityFile ,
+.Cm LocalForward,
+.Cm Match exec ,
+.Cm RemoteCommand ,
 and
-.Cm RemoteCommand
+.Cm RemoteForward
 accept the tokens %%, %C, %d, %h, %i, %L, %l, %n, %p, %r, and %u.
 .Pp
 .Cm Hostname