Fix OpenSSL SSLv2 ciphersuite downgrade vulnerability.

Security:	CVE-2015-3197
Security:	FreeBSD-SA-16:11.openssl
Approved by:	so

3 files changed, 18 insertions, 3 deletions

diff --git a/UPDATING b/UPDATING
index cc2c125df368..d3b3cb92025e 100644
--- a/UPDATING
+++ b/UPDATING
@@ -16,6 +16,10 @@ from older versions of FreeBSD, try WITHOUT_CLANG to bootstrap to the tip of
 stable/10, and then rebuild without this option. The bootstrap process from
 older version of current is a bit fragile.
 
+20160130	p12	FreeBSD-SA-16:11.openssl
+
+	Fix OpenSSL SSLv2 ciphersuite downgrade vulnerability. [SA-16:11]
+
 20160127	p11	FreeBSD-SA-16:09.ntp
 			FreeBSD-SA-16:10.linux
 
diff --git a/crypto/openssl/ssl/s2_srvr.c b/crypto/openssl/ssl/s2_srvr.c
index 4289272b73d3..8ab7a6aefac5 100644
--- a/crypto/openssl/ssl/s2_srvr.c
+++ b/crypto/openssl/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
diff --git a/sys/conf/newvers.sh b/sys/conf/newvers.sh
index e31b380752a0..eb1b8c575873 100644
--- a/sys/conf/newvers.sh
+++ b/sys/conf/newvers.sh
@@ -32,7 +32,7 @@
 
 TYPE="FreeBSD"
 REVISION="10.2"
-BRANCH="RELEASE-p11"
+BRANCH="RELEASE-p12"
 if [ "X${BRANCH_OVERRIDE}" != "X" ]; then
 	BRANCH=${BRANCH_OVERRIDE}
 fi