Merge branch 'apache:main' into configurable-clipboard-limit

Author: eugen-keeper

configure.ac

@@ -657,59 +657,40 @@ then
 fi
 
 #
-# libVNCserver support for the rfbSetDesktopSizeMsg message, which allows the
-# VNC client to send its dimensions to the server, requesting that the server
-# resize itself to match. If libvnc lacks this message, remote resize will
-# be completely disabled.
+# libVNCserver support for the rfbSetDesktopSizeMsg message and the screen
+# data structure, both of which are required in order to properly request that
+# a remote server resize its screen to match the dimensions that the client
+# sends. If libvnc lacks either this message or the screen data structure
+# remote resize will be completely disabled.
 #
 
 if test "x${have_libvncserver}" = "xyes"
 then
 
-    have_vnc_size_msg=yes
+    have_vnc_resize_support=yes
     AC_CHECK_TYPE([rfbSetDesktopSizeMsg],
-                     [], [have_vnc_size_msg=no],
+                     [], [have_vnc_resize_support=no],
                      [[#include <rfb/rfbproto.h>]])
 
-    if test "x${have_vnc_size_msg}" = "xno"
+    AC_CHECK_MEMBERS([rfbClient.screen],
+                     [], [have_vnc_resize_support=no],
+                     [[#include <rfb/rfbclient.h>]])
+
+    if test "x${have_vnc_resize_support}" = "xno"
     then
         AC_MSG_WARN([
       --------------------------------------------------------
-       No support for rfbSetDesktopSizeMsg in libvncclient.
-       VNC support for remote display resize will be disabled.
+       The libvncclient library lacks support for either the
+       rfbSetDesktopSizeMsg message or for extended screen
+       support. Resizing of remote displays will be disabled.
       --------------------------------------------------------])
     else
-        AC_DEFINE([LIBVNC_HAS_SIZE_MSG],,
+        AC_DEFINE([LIBVNC_HAS_RESIZE_SUPPORT],,
                   [Whether VNC client will support sending desktop size messages.])
     fi
 
 fi
 
-#
-# libVNCserver support for the screen structure, which allows for tracking
-# multiple screens that are part of a larger frame buffer display. If this
-# feature is missing, the VNC client may still attempt to send the display
-# resize messages, but will assume that there is a one-to-one relationship
-# between the screen size and the frame buffer size (which is currently safe
-# for Guacamole, as it lacks multi-monitor/screen support).
-#
-
-if test "x${have_libvncserver}" = "xyes"
-then
-
-    have_vnc_screen=yes
-    AC_CHECK_MEMBERS([rfbClient.screen],
-                     [], [have_vnc_screen=no],
-                     [[#include <rfb/rfbclient.h>]])
-
-    if test "x${have_vnc_screen}" = "xyes"
-    then
-        AC_DEFINE([LIBVNC_CLIENT_HAS_SCREEN],,
-                  [Whether rfbClient contains the screen data structure.])
-    fi
-
-fi
-
 #
 # libVNCserver support for the requestedResize member, which enables the 
 # client to pause frame buffer updates during a resize operation. If support

src/common-ssh/ssh.c

@@ -17,6 +17,8 @@
  * under the License.
  */
 
+#include "common/string.h"
+
 #include "common-ssh/key.h"
 #include "common-ssh/ssh.h"
 #include "common-ssh/user.h"
@@ -41,6 +43,7 @@
 #include <netinet/in.h>
 #include <pthread.h>
 #include <pwd.h>
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -64,7 +67,7 @@ GCRY_THREAD_OPTION_PTHREAD_IMPL;
 /**
  * A list of ciphers that are both FIPS-compliant, and OpenSSL-supported.
  */
-#define FIPS_COMPLIANT_CIPHERS "aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,aes192-cbc,aes256-cbc"
+#define FIPS_COMPLIANT_CIPHERS "[email protected],[email protected],aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,aes192-cbc,aes256-cbc"
 
 #ifdef OPENSSL_REQUIRES_THREADING_CALLBACKS
 /**
@@ -412,6 +415,59 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
 
 }
 
+/**
+ * Verifies if given algorithms are supported by libssh2.
+ * Writes log messages if an algorithm is not supported or
+ * could not get the list of supported algorithms from libssh2.
+ *
+ * @param client
+ *     The Guacamole client that is using SSH.
+ * 
+ * @param session
+ *     The session associated with the user to be authenticated.
+ *
+ * @param method_type
+ *      One of the libssh2 Method Type constants for libssh2_session_method_pref().
+ * 
+ * @param algs
+ *      A string with preferred list of algorithms, for example FIPS_COMPLIANT_CIPHERS.
+ *
+ */
+static void check_if_algs_are_supported(guac_client* client, LIBSSH2_SESSION* session,
+        int method_type, const char* algs) {
+
+    /* Request the list of supported algorithms/cyphers from libssh2. */
+    const char** supported_algs;
+    int supported_algs_count =
+        libssh2_session_supported_algs(session, method_type, &supported_algs);
+
+    if (supported_algs_count > 0) {
+        char** preferred_algs = guac_split(algs, ',');
+        for (int i = 0; preferred_algs[i]; i++) {
+            bool found = false;
+            /* Check if the algorithm is found in the libssh2 supported list. */
+            for (int j = 0; j < supported_algs_count; j++) {
+                if (strcmp(preferred_algs[i], supported_algs[j]) == 0) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                guac_client_log(client, GUAC_LOG_WARNING,
+                    "Preferred algorithm/cipher '%s' is not supported by libssh2", preferred_algs[i]);
+            }
+        }
+        guac_mem_free(preferred_algs);
+        /* should free if supported_algs_count is a positive number. */
+        libssh2_free(session, supported_algs);
+    }
+    else {
+        guac_client_log(client, GUAC_LOG_WARNING,
+            "libssh2 reports that no ciphers/algorithms are supported. This may be a bug in libssh2. "
+            "If the SSH connection fails, it may not be possible to log the cause here.");
+    }
+}
+
 guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
         const char* hostname, const char* port, guac_common_ssh_user* user,
         int timeout, int keepalive, const char* host_key,
@@ -445,8 +501,16 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
      * https://csrc.nist.gov/CSRC/media/projects/cryptographic-module-validation-program/documents/security-policies/140sp2906.pdf
      */
     if (guac_fips_enabled()) {
+        /*
+         * The following algorithm check is only to simplify debugging.
+         * libssh2_session_method_pref() ignores unsupported methods.
+         * So they are not sent to the remote host during protocol negotiation anyways.
+         */
+        check_if_algs_are_supported(client, session, LIBSSH2_METHOD_KEX, FIPS_COMPLIANT_KEX_ALGORITHMS);
         libssh2_session_method_pref(session, LIBSSH2_METHOD_KEX, FIPS_COMPLIANT_KEX_ALGORITHMS);
+        check_if_algs_are_supported(client, session, LIBSSH2_METHOD_CRYPT_CS, FIPS_COMPLIANT_CIPHERS);
         libssh2_session_method_pref(session, LIBSSH2_METHOD_CRYPT_CS, FIPS_COMPLIANT_CIPHERS);
+        check_if_algs_are_supported(client, session, LIBSSH2_METHOD_CRYPT_SC, FIPS_COMPLIANT_CIPHERS);
         libssh2_session_method_pref(session, LIBSSH2_METHOD_CRYPT_SC, FIPS_COMPLIANT_CIPHERS);
     }
 

src/protocols/vnc/display.c

@@ -146,7 +146,7 @@ void guac_vnc_copyrect(rfbClient* client, int src_x, int src_y, int w, int h, in
 
 }
 
-#ifdef LIBVNC_HAS_SIZE_MSG
+#ifdef LIBVNC_HAS_RESIZE_SUPPORT
 /**
  * This function does the actual work of sending the message to the RFB/VNC
  * server to request the resize, and then makes sure that the client frame
@@ -173,7 +173,11 @@ static rfbBool guac_vnc_send_desktop_size(rfbClient* client, int width, int heig
     /* Get the Guacamole client data */
     guac_client* gc = rfbClientGetClientData(client, GUAC_VNC_CLIENT_KEY);
 
-#ifdef LIBVNC_CLIENT_HAS_SCREEN
+    if (client->screen.width == 0 || client->screen.height == 0) {
+        guac_client_log(gc, GUAC_LOG_WARNING, "Screen data has not been initialized, yet.");
+        return FALSE;
+    }
+
     guac_client_log(gc, GUAC_LOG_TRACE,
             "Current screen size is %ix%i; setting new size %ix%i\n",
             rfbClientSwap16IfLE(client->screen.width),
@@ -185,19 +189,6 @@ static rfbBool guac_vnc_send_desktop_size(rfbClient* client, int width, int heig
         guac_client_log(gc, GUAC_LOG_WARNING, "Screen size has not changed, not sending update.");
         return FALSE;
     }
-#else
-    /* Don't send an update if the screen appears to be uninitialized. */
-    if (client->width == 0 || client->height == 0) {
-        guac_client_log(gc, GUAC_LOG_WARNING, "Framebuffer has not been initialized, cannot send resize.");
-        return FALSE;
-    }
-    
-    /* Don't send an update if the requested dimensions are identical to current dimensions. */
-    if (client->width == rfbClientSwap16IfLE(width) && client->height == rfbClientSwap16IfLE(height)) {
-        guac_client_log(gc, GUAC_LOG_WARNING, "Screen size has not changed, not sending update.");
-        return FALSE;
-    }
-#endif
 
     /**
      * Note: The RFB protocol requires two message types to be sent during a
@@ -219,19 +210,11 @@ static rfbBool guac_vnc_send_desktop_size(rfbClient* client, int width, int heig
     size_msg.height = rfbClientSwap16IfLE(height);
     size_msg.numberOfScreens = 1;
 
-#ifdef LIBVNC_CLIENT_HAS_SCREEN
     /* Configure the screen update message. */
     new_screen.id = GUAC_VNC_SCREEN_ID;
     new_screen.x = client->screen.x;
     new_screen.y = client->screen.y;
     new_screen.flags = client->screen.flags;
-#else
-    /* Assume screen starts at the origin. */
-    new_screen.id = GUAC_VNC_SCREEN_ID;
-    new_screen.x = 0;
-    new_screen.y = 0;
-    new_screen.flags = 0;
-#endif // LIBVNC_CLIENT_HAS_SCREEN
 
     new_screen.width = rfbClientSwap16IfLE(width);
     new_screen.height = rfbClientSwap16IfLE(height);
@@ -246,11 +229,9 @@ static rfbBool guac_vnc_send_desktop_size(rfbClient* client, int width, int heig
 
     }
 
-#ifdef LIBVNC_CLIENT_HAS_SCREEN
     /* Update the client frame buffer with the requested size. */
     client->screen.width = rfbClientSwap16IfLE(width);
     client->screen.height = rfbClientSwap16IfLE(height);
-#endif // LIBVNC_CLIENT_HAS_SCREEN
 
 #ifdef LIBVNC_CLIENT_HAS_REQUESTED_RESIZE
     client->requestedResize = FALSE;
@@ -266,6 +247,7 @@ static rfbBool guac_vnc_send_desktop_size(rfbClient* client, int width, int heig
 
     /* Update should be successful. */
     return TRUE;
+
 }
 
 void* guac_vnc_display_set_owner_size(guac_user* owner, void* data) {
@@ -323,7 +305,7 @@ void guac_vnc_display_set_size(rfbClient* client, int requested_width, int reque
     pthread_mutex_unlock(&(vnc_client->message_lock));
 
 }
-#endif // LIBVNC_HAS_SIZE_MSG
+#endif // LIBVNC_HAS_RESIZE_SUPPORT
 
 void guac_vnc_set_pixel_format(rfbClient* client, int color_depth) {
     client->format.trueColour = 1;

src/protocols/vnc/input.c

@@ -64,7 +64,7 @@ int guac_vnc_user_key_handler(guac_user* user, int keysym, int pressed) {
     return 0;
 }
 
-#ifdef LIBVNC_HAS_SIZE_MSG
+#ifdef LIBVNC_HAS_RESIZE_SUPPORT
 int guac_vnc_user_size_handler(guac_user* user, int width, int height) {
 
     guac_user_log(user, GUAC_LOG_TRACE, "Running user size handler.");
@@ -78,4 +78,4 @@ int guac_vnc_user_size_handler(guac_user* user, int width, int height) {
     return 0;
 
 }
-#endif //LIBVNC_HAS_SIZE_MSG
+#endif // LIBVNC_HAS_RESIZE_SUPPORT

src/protocols/vnc/user.c

@@ -89,11 +89,14 @@ int guac_vnc_user_join_handler(guac_user* user, int argc, char** argv) {
             user->file_handler = guac_vnc_sftp_file_handler;
 #endif
 
-#ifdef LIBVNC_HAS_SIZE_MSG
+#ifdef LIBVNC_HAS_RESIZE_SUPPORT
         /* If user is owner, set size handler. */
         if (user->owner && !settings->disable_display_resize)
             user->size_handler = guac_vnc_user_size_handler;
-#endif // LIBVNC_HAS_SIZE_MSG
+#else
+        guac_user_log(user, GUAC_LOG_WARNING,
+                "The libvncclient library does not support remote resize.");
+#endif // LIBVNC_HAS_RESIZE_SUPPORT
 
     }
 

src/protocols/vnc/vnc.c

@@ -281,8 +281,9 @@ static int guac_vnc_wait_for_messages(rfbClient* rfb_client, int msec_timeout) {
  *     True (non-zero) if messages were handled successfully, false (zero)
  *     otherwise.
  */
-static rfbBool guac_vnc_handle_messages(guac_vnc_client* vnc_client) {
+static rfbBool guac_vnc_handle_messages(guac_client* client) {
 
+    guac_vnc_client* vnc_client = (guac_vnc_client*) client->data;
     rfbClient* rfb_client = vnc_client->rfb_client;
     guac_display_layer* default_layer = guac_display_default_layer(vnc_client->display);
 
@@ -311,6 +312,31 @@ static rfbBool guac_vnc_handle_messages(guac_vnc_client* vnc_client) {
     guac_display_layer_close_raw(default_layer, context);
     vnc_client->current_context = NULL;
 
+#ifdef LIBVNC_HAS_RESIZE_SUPPORT
+    // If screen was not previously initialized, check for it and set it.
+    if (!vnc_client->rfb_screen_initialized 
+            && rfb_client->screen.width > 0
+            && rfb_client->screen.height > 0) {
+        vnc_client->rfb_screen_initialized = true;
+        guac_client_log(client, GUAC_LOG_DEBUG, "Screen is now initialized.");
+    }
+
+    /*
+     * If the screen is now or has been initialized, check to see if the initial
+     * dimensions have already been sent. If not, and resize is not disabled,
+     * send the initial size.
+     */
+    if (vnc_client->rfb_screen_initialized) {
+        guac_vnc_settings* settings = vnc_client->settings;
+        if (!vnc_client->rfb_initial_resize && !settings->disable_display_resize) {
+            guac_client_log(client, GUAC_LOG_DEBUG,
+                    "Sending initial screen size to VNC server.");
+            guac_client_for_owner(client, guac_vnc_display_set_owner_size, rfb_client);
+            vnc_client->rfb_initial_resize = true;
+        }
+    }
+#endif // LIBVNC_HAS_RESIZE_SUPPORT
+
     /* Resize the surface if VNC screen size has changed (this call
      * automatically deals with invalid dimensions and is a no-op
      * if the size has not changed) */
@@ -592,11 +618,11 @@ void* guac_vnc_client_thread(void* data) {
             guac_display_set_cursor(vnc_client->display, GUAC_DISPLAY_CURSOR_POINTER);
     }
 
-#ifdef LIBVNC_HAS_SIZE_MSG
-    /* Update the display with the owner's screen size. */
-    if (!settings->disable_display_resize)
-        guac_client_for_owner(client, guac_vnc_display_set_owner_size, rfb_client);
-#endif // LIBVNC_HAS_SIZE_MSG
+#ifdef LIBVNC_HAS_RESIZE_SUPPORT
+    /* Set initial state of the screen and resize flags. */
+    vnc_client->rfb_screen_initialized = false;
+    vnc_client->rfb_initial_resize = false;
+#endif // LIBVNC_HAS_RESIZE_SUPPORT
 
     guac_display_end_frame(vnc_client->display);
 
@@ -610,7 +636,7 @@ void* guac_vnc_client_thread(void* data) {
         if (wait_result > 0) {
 
             /* Handle any message received */
-            if (!guac_vnc_handle_messages(vnc_client)) {
+            if (!guac_vnc_handle_messages(client)) {
                 guac_client_abort(client,
                         GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR,
                         "Error handling message from VNC server.");

src/protocols/vnc/vnc.h

@@ -164,6 +164,19 @@ typedef struct guac_vnc_client {
      */
     guac_iconv_write* clipboard_writer;
 
+#ifdef LIBVNC_HAS_RESIZE_SUPPORT
+    /**
+     * Whether or not the server has sent the required message to initialize
+     * the screen data in the client.
+     */
+    bool rfb_screen_initialized;
+
+    /**
+     * Whether or not the client has sent it's starting size to the server.
+     */
+    bool rfb_initial_resize;
+#endif
+
 } guac_vnc_client;
 
 /**