gnome-ssh-askpass2.c   [plain text]


/*
 * Copyright (c) 2000-2002 Damien Miller.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* GTK2 support by Nalin Dahyabhai <nalin@redhat.com> */

/*
 * This is a simple GNOME SSH passphrase grabber. To use it, set the
 * environment variable SSH_ASKPASS to point to the location of
 * gnome-ssh-askpass before calling "ssh-add < /dev/null".
 *
 * There is only two run-time options: if you set the environment variable
 * "GNOME_SSH_ASKPASS_GRAB_SERVER=true" then gnome-ssh-askpass will grab
 * the X server. If you set "GNOME_SSH_ASKPASS_GRAB_POINTER=true", then the
 * pointer will be grabbed too. These may have some benefit to security if
 * you don't trust your X server. We grab the keyboard always.
 */

#define GRAB_TRIES	16
#define GRAB_WAIT	250 /* milliseconds */

/*
 * Compile with:
 *
 * cc -Wall `pkg-config --cflags gtk+-2.0` \
 *    gnome-ssh-askpass2.c -o gnome-ssh-askpass \
 *    `pkg-config --libs gtk+-2.0`
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <gtk/gtk.h>
#include <gdk/gdkx.h>

static void
report_failed_grab (const char *what)
{
	GtkWidget *err;

	err = gtk_message_dialog_new(NULL, 0,
				     GTK_MESSAGE_ERROR,
				     GTK_BUTTONS_CLOSE,
				     "Could not grab %s. "
				     "A malicious client may be eavesdropping "
				     "on your session.", what);
	gtk_window_set_position(GTK_WINDOW(err), GTK_WIN_POS_CENTER);
	gtk_label_set_line_wrap(GTK_LABEL((GTK_MESSAGE_DIALOG(err))->label),
				TRUE);

	gtk_dialog_run(GTK_DIALOG(err));

	gtk_widget_destroy(err);
}

static void
ok_dialog(GtkWidget *entry, gpointer dialog)
{
	g_return_if_fail(GTK_IS_DIALOG(dialog));
	gtk_dialog_response(GTK_DIALOG(dialog), GTK_RESPONSE_OK);
}

static int
passphrase_dialog(char *message)
{
	const char *failed;
	char *passphrase, *local;
	int result, grab_tries, grab_server, grab_pointer;
	GtkWidget *dialog, *entry;
	GdkGrabStatus status;

	grab_server = (getenv("GNOME_SSH_ASKPASS_GRAB_SERVER") != NULL);
	grab_pointer = (getenv("GNOME_SSH_ASKPASS_GRAB_POINTER") != NULL);
	grab_tries = 0;

	dialog = gtk_message_dialog_new(NULL, 0,
					GTK_MESSAGE_QUESTION,
					GTK_BUTTONS_OK_CANCEL,
					"%s",
					message);

	entry = gtk_entry_new();
	gtk_box_pack_start(GTK_BOX(GTK_DIALOG(dialog)->vbox), entry, FALSE,
	    FALSE, 0);
	gtk_entry_set_visibility(GTK_ENTRY(entry), FALSE);
	gtk_widget_grab_focus(entry);
	gtk_widget_show(entry);

	gtk_window_set_title(GTK_WINDOW(dialog), "OpenSSH");
	gtk_window_set_position (GTK_WINDOW(dialog), GTK_WIN_POS_CENTER);
	gtk_window_set_keep_above(GTK_WINDOW(dialog), TRUE);
	gtk_label_set_line_wrap(GTK_LABEL((GTK_MESSAGE_DIALOG(dialog))->label),
				TRUE);

	/* Make <enter> close dialog */
	gtk_dialog_set_default_response(GTK_DIALOG(dialog), GTK_RESPONSE_OK);
	g_signal_connect(G_OBJECT(entry), "activate",
			 G_CALLBACK(ok_dialog), dialog);

	gtk_window_set_keep_above(GTK_WINDOW(dialog), TRUE);

	/* Grab focus */
	gtk_widget_show_now(dialog);
	if (grab_pointer) {
		for(;;) {
			status = gdk_pointer_grab(
			   (GTK_WIDGET(dialog))->window, TRUE, 0, NULL,
			   NULL, GDK_CURRENT_TIME);
			if (status == GDK_GRAB_SUCCESS)
				break;
			usleep(GRAB_WAIT * 1000);
			if (++grab_tries > GRAB_TRIES) {
				failed = "mouse";
				goto nograb;
			}
		}
	}
	for(;;) {
		status = gdk_keyboard_grab((GTK_WIDGET(dialog))->window,
		   FALSE, GDK_CURRENT_TIME);
		if (status == GDK_GRAB_SUCCESS)
			break;
		usleep(GRAB_WAIT * 1000);
		if (++grab_tries > GRAB_TRIES) {
			failed = "keyboard";
			goto nograbkb;
		}
	}
	if (grab_server) {
		gdk_x11_grab_server();
	}

	result = gtk_dialog_run(GTK_DIALOG(dialog));

	/* Ungrab */
	if (grab_server)
		XUngrabServer(GDK_DISPLAY());
	if (grab_pointer)
		gdk_pointer_ungrab(GDK_CURRENT_TIME);
	gdk_keyboard_ungrab(GDK_CURRENT_TIME);
	gdk_flush();

	/* Report passphrase if user selected OK */
	passphrase = g_strdup(gtk_entry_get_text(GTK_ENTRY(entry)));
	if (result == GTK_RESPONSE_OK) {
		local = g_locale_from_utf8(passphrase, strlen(passphrase),
					   NULL, NULL, NULL);
		if (local != NULL) {
			puts(local);
			memset(local, '\0', strlen(local));
			g_free(local);
		} else {
			puts(passphrase);
		}
	}
		
	/* Zero passphrase in memory */
	memset(passphrase, '\b', strlen(passphrase));
	gtk_entry_set_text(GTK_ENTRY(entry), passphrase);
	memset(passphrase, '\0', strlen(passphrase));
	g_free(passphrase);
			
	gtk_widget_destroy(dialog);
	return (result == GTK_RESPONSE_OK ? 0 : -1);

	/* At least one grab failed - ungrab what we got, and report
	   the failure to the user.  Note that XGrabServer() cannot
	   fail.  */
 nograbkb:
	gdk_pointer_ungrab(GDK_CURRENT_TIME);
 nograb:
	if (grab_server)
		XUngrabServer(GDK_DISPLAY());
	gtk_widget_destroy(dialog);
	
	report_failed_grab(failed);

	return (-1);
}

int
main(int argc, char **argv)
{
	char *message;
	int result;

	gtk_init(&argc, &argv);

	if (argc > 1) {
		message = g_strjoinv(" ", argv + 1);
	} else {
		message = g_strdup("Enter your OpenSSH passphrase:");
	}

	setvbuf(stdout, 0, _IONBF, 0);
	result = passphrase_dialog(message);
	g_free(message);

	return (result);
}