1 files changed, 143 insertions, 12 deletions

diff --git a/clientloop.c b/clientloop.c
index 1e250883f..47f3c7ecd 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -59,7 +59,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: clientloop.c,v 1.135 2005/03/01 10:09:52 djm Exp $");
+RCSID("$OpenBSD: clientloop.c,v 1.141 2005/07/16 01:35:24 djm Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -140,6 +140,8 @@ int	session_ident = -1;
 struct confirm_ctx {
         int want_tty;
         int want_subsys;
+        int want_x_fwd;
+        int want_agent_fwd;
         Buffer cmd;
         char *term;
         struct termios tio;
@@ -208,6 +210,109 @@ get_current_time(void)
         return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
 }
 
+#define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
+void
+client_x11_get_proto(const char *display, const char *xauth_path,
+    u_int trusted, 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, generated = 0, do_unlink = 0, i;
+        char *xauthdir, *xauthfile;
+        struct stat st;
+
+        xauthdir = xauthfile = NULL;
+        *_proto = proto;
+        *_data = data;
+        proto[0] = data[0] = '\0';
+
+        if (xauth_path == NULL ||(stat(xauth_path, &st) == -1)) {
+                debug("No xauth program.");
+        } else {
+                if (display == NULL) {
+                        debug("x11_get_proto: DISPLAY not set");
+                        return;
+                }
+                /*
+                 * 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 (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 1200 2>" _PATH_DEVNULL,
+                                    xauth_path, 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,
+                    xauth_path,
+                    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
+         * response anyway, and substitute this data.  The X11
+         * server, however, will ignore this fake data and use
+         * whatever authentication mechanisms it was using otherwise
+         * for the local connection.
+         */
+        if (!got_data) {
+                u_int32_t rnd = 0;
+
+                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)
+                                rnd = arc4random();
+                        snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
+                            rnd & 0xff);
+                        rnd >>= 8;
+                }
+        }
+}
+
 /*
  * This is called when the interactive is entered.  This checks if there is
  * an EOF coming on stdin.  We must check this explicitly, as select() does
@@ -528,6 +633,7 @@ static void
 client_extra_session2_setup(int id, void *arg)
 {
         struct confirm_ctx *cctx = arg;
+        const char *display;
         Channel *c;
         int i;
 
@@ -536,6 +642,24 @@ client_extra_session2_setup(int id, void *arg)
         if ((c = channel_lookup(id)) == NULL)
                 fatal("%s: no channel for id %d", __func__, id);
 
+        display = getenv("DISPLAY");
+        if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
+                char *proto, *data;
+                /* Get reasonable local authentication information. */
+                client_x11_get_proto(display, options.xauth_location,
+                    options.forward_x11_trusted, &proto, &data);
+                /* Request forwarding with authentication spoofing. */
+                debug("Requesting X11 forwarding with authentication spoofing.");
+                x11_request_forwarding_with_spoofing(id, display, proto, data);
+                /* XXX wait for reply */
+        }
+
+        if (cctx->want_agent_fwd && options.forward_agent) {
+                debug("Requesting authentication agent forwarding.");
+                channel_request_start(id, "auth-agent-req@openssh.com", 0);
+                packet_send();
+        }
+
         client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
             cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env,
             client_subsystem_reply);
@@ -556,12 +680,12 @@ client_process_control(fd_set * readset)
 {
         Buffer m;
         Channel *c;
-        int client_fd, new_fd[3], ver, i, allowed;
+        int client_fd, new_fd[3], ver, allowed;
         socklen_t addrlen;
         struct sockaddr_storage addr;
         struct confirm_ctx *cctx;
         char *cmd;
-        u_int len, env_len, command, flags;
+        u_int i, len, env_len, command, flags;
         uid_t euid;
         gid_t egid;
 
@@ -601,7 +725,7 @@ client_process_control(fd_set * readset)
                 buffer_free(&m);
                 return;
         }
-        if ((ver = buffer_get_char(&m)) != 1) {
+        if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
                 error("%s: wrong client version %d", __func__, ver);
                 buffer_free(&m);
                 close(client_fd);
@@ -616,24 +740,26 @@ client_process_control(fd_set * readset)
 
         switch (command) {
         case SSHMUX_COMMAND_OPEN:
-                if (options.control_master == 2)
+                if (options.control_master == SSHCTL_MASTER_ASK ||
+                    options.control_master == SSHCTL_MASTER_AUTO_ASK)
                         allowed = ask_permission("Allow shared connection "
                             "to %s? ", host);
                 /* continue below */
                 break;
         case SSHMUX_COMMAND_TERMINATE:
-                if (options.control_master == 2)
+                if (options.control_master == SSHCTL_MASTER_ASK ||
+                    options.control_master == SSHCTL_MASTER_AUTO_ASK)
                         allowed = ask_permission("Terminate shared connection "
                             "to %s? ", host);
                 if (allowed)
                         quit_pending = 1;
-                /* FALLTHROUGH */       
+                /* FALLTHROUGH */
         case SSHMUX_COMMAND_ALIVE_CHECK:
                 /* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */
                 buffer_clear(&m);
                 buffer_put_int(&m, allowed);
                 buffer_put_int(&m, getpid());
-                if (ssh_msg_send(client_fd, /* version */1, &m) == -1) {
+                if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
                         error("%s: client msg_send failed", __func__);
                         close(client_fd);
                         buffer_free(&m);
@@ -653,7 +779,7 @@ client_process_control(fd_set * readset)
         buffer_clear(&m);
         buffer_put_int(&m, allowed);
         buffer_put_int(&m, getpid());
-        if (ssh_msg_send(client_fd, /* version */1, &m) == -1) {
+        if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
                 error("%s: client msg_send failed", __func__);
                 close(client_fd);
                 buffer_free(&m);
@@ -674,7 +800,7 @@ client_process_control(fd_set * readset)
                 buffer_free(&m);
                 return;
         }
-        if ((ver = buffer_get_char(&m)) != 1) {
+        if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
                 error("%s: wrong client version %d", __func__, ver);
                 buffer_free(&m);
                 close(client_fd);
@@ -685,6 +811,8 @@ client_process_control(fd_set * readset)
         memset(cctx, 0, sizeof(*cctx));
         cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0;
         cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0;
+        cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
+        cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
         cctx->term = buffer_get_string(&m, &len);
 
         cmd = buffer_get_string(&m, &len);
@@ -718,7 +846,7 @@ client_process_control(fd_set * readset)
 
         /* This roundtrip is just for synchronisation of ttymodes */
         buffer_clear(&m);
-        if (ssh_msg_send(client_fd, /* version */1, &m) == -1) {
+        if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
                 error("%s: client msg_send failed", __func__);
                 close(client_fd);
                 close(new_fd[0]);
@@ -866,7 +994,10 @@ process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
         u_char ch;
         char *s;
 
-        for (i = 0; i < len; i++) {
+        if (len <= 0)
+                return (0);
+
+        for (i = 0; i < (u_int)len; i++) {
                 /* Get one character at a time. */
                 ch = buf[i];