- markus@cvs.openbsd.org 2003/10/11 08:24:08
[readconf.c readconf.h ssh.1 ssh.c ssh_config.5]
remote x11 clients are now untrusted by default, uses xauth(8) to generate
untrusted cookies; ForwardX11Trusted=yes restores old behaviour.
ok deraadt; feedback and ok djm/fries
diff --git a/ssh.c b/ssh.c
index 35418f6..39d1b2f 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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;
}
}