From 800567a613510c77a55decac4d25fea154d1ee22 Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Wed, 1 Jul 2015 18:10:38 +0100
Subject: [PATCH] ui: convert VNC to use generic cipher API

Switch the VNC server over to use the generic cipher API, this
allows it to use the pluggable DES implementations, instead of
being hardcoded to use QEMU's built-in impl.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-11-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 ui/vnc.c | 52 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 41 insertions(+), 11 deletions(-)

diff --git a/ui/vnc.c b/ui/vnc.c
index 7d844f7195..94e4f19a60 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -49,7 +49,7 @@ static const struct timeval VNC_REFRESH_STATS = { 0, 500000 };
 static const struct timeval VNC_REFRESH_LOSSY = { 2, 0 };
 
 #include "vnc_keysym.h"
-#include "crypto/desrfb.h"
+#include "crypto/cipher.h"
 
 static QTAILQ_HEAD(, VncDisplay) vnc_displays =
     QTAILQ_HEAD_INITIALIZER(vnc_displays);
@@ -2517,9 +2517,11 @@ static void make_challenge(VncState *vs)
 static int protocol_client_auth_vnc(VncState *vs, uint8_t *data, size_t len)
 {
     unsigned char response[VNC_AUTH_CHALLENGE_SIZE];
-    int i, j, pwlen;
+    size_t i, pwlen;
     unsigned char key[8];
     time_t now = time(NULL);
+    QCryptoCipher *cipher;
+    Error *err = NULL;
 
     if (!vs->vd->password) {
         VNC_DEBUG("No password configured on server");
@@ -2536,9 +2538,29 @@ static int protocol_client_auth_vnc(VncState *vs, uint8_t *data, size_t len)
     pwlen = strlen(vs->vd->password);
     for (i=0; i<sizeof(key); i++)
         key[i] = i<pwlen ? vs->vd->password[i] : 0;
-    deskey(key, EN0);
-    for (j = 0; j < VNC_AUTH_CHALLENGE_SIZE; j += 8)
-        des(response+j, response+j);
+
+    cipher = qcrypto_cipher_new(
+        QCRYPTO_CIPHER_ALG_DES_RFB,
+        QCRYPTO_CIPHER_MODE_ECB,
+        key, G_N_ELEMENTS(key),
+        &err);
+    if (!cipher) {
+        VNC_DEBUG("Cannot initialize cipher %s",
+                  error_get_pretty(err));
+        error_free(err);
+        goto reject;
+    }
+
+    if (qcrypto_cipher_decrypt(cipher,
+                               vs->challenge,
+                               response,
+                               VNC_AUTH_CHALLENGE_SIZE,
+                               &err) < 0) {
+        VNC_DEBUG("Cannot encrypt challenge %s",
+                  error_get_pretty(err));
+        error_free(err);
+        goto reject;
+    }
 
     /* Compare expected vs actual challenge response */
     if (memcmp(response, data, VNC_AUTH_CHALLENGE_SIZE) != 0) {
@@ -3484,12 +3506,20 @@ void vnc_display_open(const char *id, Error **errp)
     }
 
     password = qemu_opt_get_bool(opts, "password", false);
-    if (password && fips_get_state()) {
-        error_setg(errp,
-                   "VNC password auth disabled due to FIPS mode, "
-                   "consider using the VeNCrypt or SASL authentication "
-                   "methods as an alternative");
-        goto fail;
+    if (password) {
+        if (fips_get_state()) {
+            error_setg(errp,
+                       "VNC password auth disabled due to FIPS mode, "
+                       "consider using the VeNCrypt or SASL authentication "
+                       "methods as an alternative");
+            goto fail;
+        }
+        if (!qcrypto_cipher_supports(
+                QCRYPTO_CIPHER_ALG_DES_RFB)) {
+            error_setg(errp,
+                       "Cipher backend does not support DES RFB algorithm");
+            goto fail;
+        }
     }
 
     reverse = qemu_opt_get_bool(opts, "reverse", false);