1 files changed, 68 insertions, 24 deletions

diff --git a/ssh.c b/ssh.c
index 35418f693..39d1b2f6a 100644
--- a/ssh.c
+++ b/ssh.c
@@ -13,7 +13,7 @@
  * called by a name other than "ssh" or "Secure Shell".
  *
  * Copyright (c) 1999 Niels Provos.  All rights reserved.
- * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  *
  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  * in Canada (German citizen).
@@ -40,7 +40,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: ssh.c,v 1.201 2003/09/01 18:15:50 markus Exp $");
+RCSID("$OpenBSD: ssh.c,v 1.202 2003/10/11 08:24:08 markus Exp $");
 
 #include <openssl/evp.h>
 #include <openssl/err.h>
@@ -155,6 +155,7 @@ usage(void)
         fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
         fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
         fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
+        fprintf(stderr, "  -Y          Enable trusted X11 connection forwarding.\n");
         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
         fprintf(stderr, "  -i file     Identity for public key authentication "
             "(default: ~/.ssh/identity)\n");
@@ -264,7 +265,7 @@ main(int ac, char **av)
 
 again:
         while ((opt = getopt(ac, av,
-            "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {
+            "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVXY")) != -1) {
                 switch (opt) {
                 case '1':
                         options.protocol = SSH_PROTO_1;
@@ -291,6 +292,10 @@ again:
                 case 'X':
                         options.forward_x11 = 1;
                         break;
+                case 'Y':
+                        options.forward_x11 = 1;
+                        options.forward_x11_trusted = 1;
+                        break;
                 case 'g':
                         options.gateway_ports = 1;
                         break;
@@ -721,19 +726,25 @@ again:
         return exit_status;
 }
 
+#define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
+
 static void
 x11_get_proto(char **_proto, char **_data)
 {
+        char cmd[1024];
         char line[512];
+        char xdisplay[512];
         static char proto[512], data[512];
         FILE *f;
-        int got_data = 0, i;
-        char *display;
+        int got_data = 0, generated = 0, do_unlink = 0, i;
+        char *display, *xauthdir, *xauthfile;
         struct stat st;
 
+        xauthdir = xauthfile = NULL;
         *_proto = proto;
         *_data = data;
         proto[0] = data[0] = '\0';
+
         if (!options.xauth_location ||
             (stat(options.xauth_location, &st) == -1)) {
                 debug("No xauth program.");
@@ -742,28 +753,59 @@ x11_get_proto(char **_proto, char **_data)
                         debug("x11_get_proto: DISPLAY not set");
                         return;
                 }
-                /* Try to get Xauthority information for the display. */
-                if (strncmp(display, "localhost:", 10) == 0)
-                        /*
-                         * Handle FamilyLocal case where $DISPLAY does
-                         * not match an authorization entry.  For this we
-                         * just try "xauth list unix:displaynum.screennum".
-                         * XXX: "localhost" match to determine FamilyLocal
-                         *      is not perfect.
-                         */
-                        snprintf(line, sizeof line, "%s list unix:%s 2>"
-                            _PATH_DEVNULL, options.xauth_location, display+10);
-                else
-                        snprintf(line, sizeof line, "%s list %.200s 2>"
-                            _PATH_DEVNULL, options.xauth_location, display);
-                debug2("x11_get_proto: %s", line);
-                f = popen(line, "r");
+                /*
+                 * Handle FamilyLocal case where $DISPLAY does
+                 * not match an authorization entry.  For this we
+                 * just try "xauth list unix:displaynum.screennum".
+                 * XXX: "localhost" match to determine FamilyLocal
+                 *      is not perfect.
+                 */
+                if (strncmp(display, "localhost:", 10) == 0) {
+                        snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
+                            display + 10);
+                        display = xdisplay;
+                }
+                if (options.forward_x11_trusted == 0) {
+                        xauthdir = xmalloc(MAXPATHLEN);
+                        xauthfile = xmalloc(MAXPATHLEN);
+                        strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
+                        if (mkdtemp(xauthdir) != NULL) {
+                                do_unlink = 1;
+                                snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
+                                    xauthdir);
+                                snprintf(cmd, sizeof(cmd),
+                                    "%s -f %s generate %s " SSH_X11_PROTO
+                                    " untrusted timeout 120 2>" _PATH_DEVNULL,
+                                    options.xauth_location, xauthfile, display);
+                                debug2("x11_get_proto: %s", cmd);
+                                if (system(cmd) == 0)
+                                        generated = 1;
+                        }
+                }
+                snprintf(cmd, sizeof(cmd),
+                    "%s %s%s list %s . 2>" _PATH_DEVNULL,
+                    options.xauth_location,
+                    generated ? "-f " : "" ,
+                    generated ? xauthfile : "",
+                    display);
+                debug2("x11_get_proto: %s", cmd);
+                f = popen(cmd, "r");
                 if (f && fgets(line, sizeof(line), f) &&
                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
                         got_data = 1;
                 if (f)
                         pclose(f);
         }
+
+        if (do_unlink) {
+                unlink(xauthfile);
+                rmdir(xauthdir);
+        }
+        if (xauthdir)
+                xfree(xauthdir);
+        if (xauthfile)
+                xfree(xauthfile);
+
         /*
          * If we didn't get authentication data, just make up some
          * data.  The forwarding code will check the validity of the
@@ -775,12 +817,14 @@ x11_get_proto(char **_proto, char **_data)
         if (!got_data) {
                 u_int32_t rand = 0;
 
-                logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
-                strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
+                logit("Warning: No xauth data; "
+                    "using fake authentication data for X11 forwarding.");
+                strlcpy(proto, SSH_X11_PROTO, sizeof proto);
                 for (i = 0; i < 16; i++) {
                         if (i % 4 == 0)
                                 rand = arc4random();
-                        snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
+                        snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
+                            rand & 0xff);
                         rand >>= 8;
                 }
         }