From d81a1600588b726c2bdccda7efad3cc7a87d6245 Mon Sep 17 00:00:00 2001
From: Viktor Dukhovni <openssl-users@dukhovni.org>
Date: Wed, 30 Dec 2015 22:44:51 -0500
Subject: [PATCH] Better SSLv2 cipher-suite enforcement

Based on patch by: Nimrod Aviram <nimrod.aviram@gmail.com>

CVE-2015-3197

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>

Upstream-Status: Backport
https://github.com/openssl/openssl/commit/d81a1600588b726c2bdccda7efad3cc7a87d6245

CVE: CVE-2015-3197
Signed-off-by: Armin Kuster <akuster@mvista.com>

---
 ssl/s2_srvr.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Index: openssl-1.0.2d/ssl/s2_srvr.c
===================================================================
--- openssl-1.0.2d.orig/ssl/s2_srvr.c
+++ openssl-1.0.2d/ssl/s2_srvr.c
@@ -402,7 +402,7 @@ static int get_client_master_key(SSL *s)
         }
 
         cp = ssl2_get_cipher_by_char(p);
-        if (cp == NULL) {
+        if (cp == NULL || sk_SSL_CIPHER_find(s->session->ciphers, cp) < 0) {
             ssl2_return_error(s, SSL2_PE_NO_CIPHER);
             SSLerr(SSL_F_GET_CLIENT_MASTER_KEY, SSL_R_NO_CIPHER_MATCH);
             return (-1);
@@ -687,8 +687,12 @@ static int get_client_hello(SSL *s)
             prio = cs;
             allow = cl;
         }
+
+        /* Generate list of SSLv2 ciphers shared between client and server */
         for (z = 0; z < sk_SSL_CIPHER_num(prio); z++) {
-            if (sk_SSL_CIPHER_find(allow, sk_SSL_CIPHER_value(prio, z)) < 0) {
+            const SSL_CIPHER *cp = sk_SSL_CIPHER_value(prio, z);
+            if ((cp->algorithm_ssl & SSL_SSLV2) == 0 ||
+                sk_SSL_CIPHER_find(allow, cp) < 0) {
                 (void)sk_SSL_CIPHER_delete(prio, z);
                 z--;
             }
@@ -697,6 +701,13 @@ static int get_client_hello(SSL *s)
             sk_SSL_CIPHER_free(s->session->ciphers);
             s->session->ciphers = prio;
         }
+
+        /* Make sure we have at least one cipher in common */
+        if (sk_SSL_CIPHER_num(s->session->ciphers) == 0) {
+            ssl2_return_error(s, SSL2_PE_NO_CIPHER);
+            SSLerr(SSL_F_GET_CLIENT_HELLO, SSL_R_NO_CIPHER_MATCH);
+            return -1;
+        }
         /*
          * s->session->ciphers should now have a list of ciphers that are on
          * both the client and server. This list is ordered by the order the