- djm@cvs.openbsd.org 2005/06/06 11:20:36

[auth.c auth.h misc.c misc.h ssh.c ssh_config.5 sshconnect.c]
     introduce a generic %foo expansion function. replace existing % expansion
     and add expansion to ControlPath; ok markus@

ChangeLog

@@ -3,7 +3,10 @@
    - jaredy@cvs.openbsd.org 2005/06/07 13:25:23
      [progressmeter.c]
      catch SIGWINCH and resize progress meter accordingly; ok markus dtucker
-
+   - djm@cvs.openbsd.org 2005/06/06 11:20:36
+     [auth.c auth.h misc.c misc.h ssh.c ssh_config.5 sshconnect.c]
+     introduce a generic %foo expansion function. replace existing % expansion 
+     and add expansion to ControlPath; ok markus@
 
 20050609
  - (dtucker) [cipher.c openbsd-compat/Makefile.in
@@ -2699,4 +2702,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.3816 2005/06/16 03:18:04 djm Exp $
+$Id: ChangeLog,v 1.3817 2005/06/16 03:18:34 djm Exp $

auth.c

@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth.c,v 1.58 2005/03/14 11:44:42 dtucker Exp $");
+RCSID("$OpenBSD: auth.c,v 1.59 2005/06/06 11:20:36 djm Exp $");
 
 #ifdef HAVE_LOGIN_H
 #include <login.h>
@@ -326,64 +326,41 @@ auth_root_allowed(char *method)
  *
  * This returns a buffer allocated by xmalloc.
  */
-char *
+static char *
-expand_filename(const char *filename, struct passwd *pw)
+expand_authorized_keys(const char *filename, struct passwd *pw)
 {
-	Buffer buffer;
+	char *file, *ret;
-	char *file;
-	const char *cp;
 
-	/*
+	file = percent_expand(filename, "h", pw->pw_dir,
-	 * Build the filename string in the buffer by making the appropriate
+	    "u", pw->pw_name, (char *)NULL);
-	 * substitutions to the given file name.
-	 */
-	buffer_init(&buffer);
-	for (cp = filename; *cp; cp++) {
-		if (cp[0] == '%' && cp[1] == '%') {
-			buffer_append(&buffer, "%", 1);
-			cp++;
-			continue;
-		}
-		if (cp[0] == '%' && cp[1] == 'h') {
-			buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
-			cp++;
-			continue;
-		}
-		if (cp[0] == '%' && cp[1] == 'u') {
-			buffer_append(&buffer, pw->pw_name,
-			    strlen(pw->pw_name));
-			cp++;
-			continue;
-		}
-		buffer_append(&buffer, cp, 1);
-	}
-	buffer_append(&buffer, "\0", 1);
 
 	/*
 	 * Ensure that filename starts anchored. If not, be backward
 	 * compatible and prepend the '%h/'
 	 */
-	file = xmalloc(MAXPATHLEN);
+	if (*file == '/')
-	cp = buffer_ptr(&buffer);
+		return (file);
-	if (*cp != '/')
-		snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
-	else
-		strlcpy(file, cp, MAXPATHLEN);
 
-	buffer_free(&buffer);
+	ret = xmalloc(MAXPATHLEN);
-	return file;
+	if (strlcpy(ret, pw->pw_dir, MAXPATHLEN) >= MAXPATHLEN ||
+	    strlcat(ret, "/", MAXPATHLEN) >= MAXPATHLEN ||
+	    strlcat(ret, file, MAXPATHLEN) >= MAXPATHLEN)
+		fatal("expand_authorized_keys: path too long");
+
+	xfree(file);
+	return (ret);
 }
 
 char *
 authorized_keys_file(struct passwd *pw)
 {
-	return expand_filename(options.authorized_keys_file, pw);
+	return expand_authorized_keys(options.authorized_keys_file, pw);
 }
 
 char *
 authorized_keys_file2(struct passwd *pw)
 {
-	return expand_filename(options.authorized_keys_file2, pw);
+	return expand_authorized_keys(options.authorized_keys_file2, pw);
 }
 
 /* return ok if key exists in sysfile or userfile */

auth.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: auth.h,v 1.50 2004/05/23 23:59:53 dtucker Exp $	*/
+/*	$OpenBSD: auth.h,v 1.51 2005/06/06 11:20:36 djm Exp $	*/
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -163,7 +163,6 @@ char	*get_challenge(Authctxt *);
 int	verify_response(Authctxt *, const char *);
 void	abandon_challenge_response(Authctxt *);
 
-char	*expand_filename(const char *, struct passwd *);
 char	*authorized_keys_file(struct passwd *);
 char	*authorized_keys_file2(struct passwd *);
 

misc.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2005 Damien Miller.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -23,7 +24,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: misc.c,v 1.30 2005/04/09 04:32:54 djm Exp $");
+RCSID("$OpenBSD: misc.c,v 1.31 2005/06/06 11:20:36 djm Exp $");
 
 #include "misc.h"
 #include "log.h"
@@ -420,6 +421,68 @@ tilde_expand_filename(const char *filename, uid_t uid)
 	return (xstrdup(ret));
 }
 
+/*
+ * Expand a string with a set of %[char] escapes. A number of escapes may be
+ * specified as (char *escape_chars, char *replacement) pairs. The list must
+ * be terminated by an escape_char of -1. Returns replaced string in memory
+ * allocated by xmalloc.
+ */
+char *
+percent_expand(const char *string, ...)
+{
+#define EXPAND_MAX_KEYS	16
+	struct {
+		const char *key;
+		const char *repl;
+	} keys[EXPAND_MAX_KEYS];
+	int num_keys, i, j;
+	char buf[4096];
+	va_list ap;
+
+	/* Gather keys */
+	va_start(ap, string);
+	for (num_keys = 0; num_keys < EXPAND_MAX_KEYS; num_keys++) {
+		keys[num_keys].key = va_arg(ap, char *);
+		if (keys[num_keys].key == NULL)
+			break;
+		keys[num_keys].repl = va_arg(ap, char *);
+		if (keys[num_keys].repl == NULL)
+			fatal("percent_expand: NULL replacement");
+	}
+	va_end(ap);
+
+	if (num_keys >= EXPAND_MAX_KEYS)
+		fatal("percent_expand: too many keys");
+
+	/* Expand string */
+	*buf = '\0';
+	for (i = 0; *string != '\0'; string++) {
+		if (*string != '%') {
+ append:
+			buf[i++] = *string;
+			if (i >= sizeof(buf))
+				fatal("percent_expand: string too long");
+			buf[i] = '\0';
+			continue;
+		}
+		string++;
+		if (*string == '%')
+			goto append;
+		for (j = 0; j < num_keys; j++) {
+			if (strchr(keys[j].key, *string) != NULL) {
+				i = strlcat(buf, keys[j].repl, sizeof(buf));
+				if (i >= sizeof(buf))
+					fatal("percent_expand: string too long");
+				break;
+			}
+		}
+		if (j >= num_keys)
+			fatal("percent_expand: unknown key %%%c", *string);
+	}
+	return (xstrdup(buf));
+#undef EXPAND_MAX_KEYS
+}
+
 /*
  * Read an entire line from a public key file into a static buffer, discarding
  * lines that exceed the buffer size.  Returns 0 on success, -1 on failure.

misc.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: misc.h,v 1.22 2005/04/09 04:32:54 djm Exp $	*/
+/*	$OpenBSD: misc.h,v 1.23 2005/06/06 11:20:36 djm Exp $	*/
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -25,6 +25,7 @@ char	*cleanhostname(char *);
 char	*colon(char *);
 long	 convtime(const char *);
 char	*tilde_expand_filename(const char *, uid_t);
+char	*percent_expand(const char *, ...) __attribute__((sentinel));
 
 struct passwd *pwcopy(struct passwd *);
 

ssh.c

@@ -40,7 +40,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: ssh.c,v 1.240 2005/05/27 08:30:37 djm Exp $");
+RCSID("$OpenBSD: ssh.c,v 1.241 2005/06/06 11:20:36 djm Exp $");
 
 #include <openssl/evp.h>
 #include <openssl/err.h>
@@ -609,8 +609,12 @@ again:
 		options.proxy_command = NULL;
 
 	if (options.control_path != NULL) {
-		options.control_path = tilde_expand_filename(
+		snprintf(buf, sizeof(buf), "%d", options.port);
-		   options.control_path, original_real_uid);
+		cp = tilde_expand_filename(options.control_path,
+		    original_real_uid);
+		options.control_path = percent_expand(cp, "p", buf, "h", host,
+		    "r", options.user, (char *)NULL);
+		xfree(cp);
 	}
 	if (mux_command != 0 && options.control_path == NULL)
 		fatal("No ControlPath specified for \"-O\" command");

ssh_config.5

@@ -34,7 +34,7 @@
 .\" (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 1.54 2005/05/23 23:32:46 djm Exp $
+.\" $OpenBSD: ssh_config.5,v 1.55 2005/06/06 11:20:36 djm Exp $
 .Dd September 25, 1999
 .Dt SSH_CONFIG 5
 .Os
@@ -279,10 +279,17 @@ can not be opened,
 .Nm ssh
 will continue without connecting to a master instance.
 .It Cm ControlPath
-Specify the path to the control socket used for connection sharing.
+Specify the path to the control socket used for connection sharing as described
-See
+in the
 .Cm ControlMaster
-above.
+section above.
+In the path,
+.Ql %h
+will be substituted by the target host name,
+.Ql %p
+the port and
+.Ql %r
+by the remote login username.
 .It Cm DynamicForward
 Specifies that a TCP/IP port on the local machine be forwarded
 over the secure channel, and the application

sshconnect.c

@@ -13,7 +13,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect.c,v 1.163 2005/05/24 17:32:44 avsm Exp $");
+RCSID("$OpenBSD: sshconnect.c,v 1.164 2005/06/06 11:20:36 djm Exp $");
 
 #include <openssl/bn.h>
 
@@ -59,12 +59,11 @@ static void warn_changed_key(Key *);
 static int
 ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
 {
-	Buffer command;
+	char *command_string, *tmp;
-	const char *cp;
-	char *command_string;
 	int pin[2], pout[2];
 	pid_t pid;
 	char strport[NI_MAXSERV];
+	size_t len;
 
 	/* Convert the port number into a string. */
 	snprintf(strport, sizeof strport, "%hu", port);
@@ -76,31 +75,13 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
 	 * Use "exec" to avoid "sh -c" processes on some platforms
 	 * (e.g. Solaris)
 	 */
-	buffer_init(&command);
+	len = strlen(proxy_command) + 6;
-	buffer_append(&command, "exec ", 5);
+	tmp = xmalloc(len);
-
+	strlcpy(tmp, "exec ", len);
-	for (cp = proxy_command; *cp; cp++) {
+	strlcat(tmp, proxy_command, len);
-		if (cp[0] == '%' && cp[1] == '%') {
+	command_string = percent_expand(tmp, "h", host,
-			buffer_append(&command, "%", 1);
+	    "p", strport, (char *)NULL);
-			cp++;
+	xfree(tmp);
-			continue;
-		}
-		if (cp[0] == '%' && cp[1] == 'h') {
-			buffer_append(&command, host, strlen(host));
-			cp++;
-			continue;
-		}
-		if (cp[0] == '%' && cp[1] == 'p') {
-			buffer_append(&command, strport, strlen(strport));
-			cp++;
-			continue;
-		}
-		buffer_append(&command, cp, 1);
-	}
-	buffer_append(&command, "\0", 1);
-
-	/* Get the final command string. */
-	command_string = buffer_ptr(&command);
 
 	/* Create pipes for communicating with the proxy. */
 	if (pipe(pin) < 0 || pipe(pout) < 0)
@@ -154,7 +135,7 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
 	close(pout[1]);
 
 	/* Free the command name. */
-	buffer_free(&command);
+	xfree(command_string);
 
 	/* Set the connection file descriptors. */
 	packet_set_connection(pout[0], pin[1]);