[Spice-devel] [PATCH spice-server v2] Use TLS version 1.0 or better

[David Jaša]

When creating a TLS socket, both spice-server and spice-gtk currently
call SSL_CTX_new(TLSv1_method()). The TLSv1_method() function set the
protocol version to TLS 1.0 exclusively. The correct way to support
multiple protocol versions is to call SSLv23_method() in spite of its
scary name. This method will enable all protocol versions deemed secure
by openssl project. The protocol suite may be further narrowed down by
setting respective SSL_OP_NO_<version_code> options of SSL context. This
possibility is used in this patch in order to block use of SSLv3 that is
enabled by default in openssl as of now but spice has never used it.

v2: fix error pointed out by Daniel P. Berrangé
---
 server/reds.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/server/reds.c b/server/reds.c
index 2a0002b..fef666d 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -3221,6 +3221,14 @@ static int reds_init_ssl(void)
     SSL_METHOD *ssl_method;
 #endif
     int return_code;
+    /* When some other SSL/TLS version becomes obsolete, add it to this
+     * variable.
+     *
+     * Note that SSLv23_method() even with no SSL_OP_NO_* options uses
+     * just protocol versions deemed secure by openssl project so the
+     * SSL_OP_NO_SSLv2 is already redundant and SSL_OP_NO_SSLv3 option is
+     * present just in order to allow only currently-availabe version or
+     * better. */
     long ssl_options = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
 
     /* Global system initialization*/
@@ -3228,7 +3236,7 @@ static int reds_init_ssl(void)
     SSL_load_error_strings();
 
     /* Create our context*/
-    ssl_method = TLSv1_method();
+    ssl_method = SSLv23_method();
     reds->ctx = SSL_CTX_new(ssl_method);
     if (!reds->ctx) {
         spice_warning("Could not allocate new SSL context");
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