postgresql-9.4-ssl-protocols.diff

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 2fb9217..50bd51f 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1027,6 +1027,34 @@ include_dir 'conf.d'
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-ssl-protocols" xreflabel="ssl_protocols">
+      <term><varname>ssl_protocols</varname> (<type>string</type>)</term>
+      <indexterm>
+       <primary><varname>ssl_protocols</> configuration parameter</primary>
+      </indexterm>
+      <listitem>
+       <para>
+        Specifies a colon-separated list of <acronym>SSL</> protocols that are
+        allowed to be used on secure connections. Each entry in the list can
+        be prefixed by a <literal>+</> (add to the current list)
+        or <literal>-</> (remove from the current list). If no prefix is used,
+        the list is replaced with the specified protocol.
+       </para>
+       <para>
+        The full list of supported protocols can be found in the
+        the <application>openssl</> manual page.  In addition to the names of
+        individual protocols, the following keywords can be
+        used: <literal>ALL</> (all protocols supported by the underlying
+        crypto library), <literal>SSL</> (all supported versions
+        of <acronym>SSL</>) and <literal>TLS</> (all supported versions
+        of <acronym>TLS</>).
+       </para>
+       <para>
+        The default is <literal>ALL:-SSL</literal>.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="guc-ssl-ciphers" xreflabel="ssl_ciphers">
       <term><varname>ssl_ciphers</varname> (<type>string</type>)
       <indexterm>
diff --git a/src/backend/libpq/be-secure.c b/src/backend/libpq/be-secure.c
index 89c30d0..acebdc2 100644
--- a/src/backend/libpq/be-secure.c
+++ b/src/backend/libpq/be-secure.c
@@ -90,6 +90,7 @@ static void initialize_SSL(void);
 static int	open_server_SSL(Port *);
 static void close_SSL(Port *);
 static const char *SSLerrmessage(void);
+static long parse_SSL_protocols(const char *str);
 #endif
 
 char	   *ssl_cert_file;
@@ -112,7 +113,8 @@ static SSL_CTX *SSL_context = NULL;
 static bool ssl_loaded_verify_locations = false;
 #endif
 
-/* GUC variable controlling SSL cipher list */
+/* GUC variables controlling SSL protocol and cipher list */
+char	   *SSLProtocols = NULL;
 char	   *SSLCipherSuites = NULL;
 
 /* GUC variable for default ECHD curve. */
@@ -887,15 +889,16 @@ initialize_SSL(void)
 							SSLerrmessage())));
 	}
 
-	/* set up ephemeral DH keys, and disallow SSL v2/v3 while at it */
+	/* set up ephemeral DH keys */
 	SSL_CTX_set_tmp_dh_callback(SSL_context, tmp_dh_cb);
-	SSL_CTX_set_options(SSL_context,
-						SSL_OP_SINGLE_DH_USE |
-						SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
+	SSL_CTX_set_options(SSL_context, SSL_OP_SINGLE_DH_USE);
 
 	/* set up ephemeral ECDH keys */
 	initialize_ecdh();
 
+	/* set up the allowed protocol list */
+	SSL_CTX_set_options(SSL_context, parse_SSL_protocols(SSLProtocols));
+
 	/* set up the allowed cipher list */
 	if (SSL_CTX_set_cipher_list(SSL_context, SSLCipherSuites) != 1)
 		elog(FATAL, "could not set the cipher list (no valid ciphers available)");
@@ -1158,4 +1161,106 @@ SSLerrmessage(void)
 	return errbuf;
 }
 
+/*
+ *	Parse the SSL allowed protocol list
+ *
+ *	The logic here is inverted.  OpenSSL does not take a list of
+ *	protocols to use, but a list of protocols to avoid.  We use the
+ *	same bits with the opposite meaning, then invert the result.
+ */
+
+#define SSL_PROTO_SSLv2		SSL_OP_NO_SSLv2
+#define SSL_PROTO_SSLv3		SSL_OP_NO_SSLv3
+#define SSL_PROTO_SSL		(SSL_PROTO_SSLv2 | SSL_PROTO_SSLv3)
+#define SSL_PROTO_TLSv1		SSL_OP_NO_TLSv1
+#ifdef SSL_OP_NO_TLSv1_1
+#define SSL_PROTO_TLSv1_1	SSL_OP_NO_TLSv1_1
+#else
+#define SSL_PROTO_TLSv1_1	0
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+#define SSL_PROTO_TLSv1_2	SSL_OP_NO_TLSv1_2
+#else
+#define SSL_PROTO_TLSv1_2	0
+#endif
+#define SSL_PROTO_TLS		(SSL_PROTO_TLSv1 | SSL_PROTO_TLSv1_1 | SSL_PROTO_TLSv1_2)
+#define SSL_PROTO_ALL		(SSL_PROTO_SSL | SSL_PROTO_TLS)
+#define SSL_PROTO_NONE		0
+
+#define str_is_token(str, tok, len) \
+	(len == sizeof(tok) - 1 && pg_strncasecmp(str, tok, len) == 0)
+
+static long
+parse_SSL_protocols(const char *str)
+{
+	long current, result;
+	const char *p, *q;
+	int action;
+
+	/*
+	 * Iterate over the colon-separated list of protocols.  If a protocol is
+	 * preceded by a +, it is added to the list.  If it is preceded by a -, it
+	 * is removed from the list.  If it is not preceded by anything, the list
+	 * is set to exactly that protocol.  "ALL" can be used to indicate all
+	 * protocols, "NONE" to indicate no protocols "SSL" to indicate all SSL
+	 * protocols and "TLS" to indicate all TLS protocols.  The parser accepts
+	 * "SSLv2", "SSLv3" and "SSL", but they are removed after parsing.
+	 */
+	result = SSL_PROTO_NONE;
+	for (p = q = str; *q; p = q + 1) {
+		for (q = p; *q && *q != ':'; ++q)
+			/* nothing */ ;
+		if (*p == '-' || *p == '+')
+			action = *p++;
+		else
+			action = '=';
+		if (str_is_token(p, "ALL", q - p))
+			current = SSL_PROTO_ALL;
+		else if (str_is_token(p, "NONE", q - p))
+			current = SSL_PROTO_NONE;
+		else if (str_is_token(p, SSL_TXT_SSLV2, q - p))
+			current = SSL_PROTO_SSLv2;
+		else if (str_is_token(p, SSL_TXT_SSLV3, q - p))
+			current = SSL_PROTO_SSLv3;
+		else if (str_is_token(p, "SSL", q - p))
+			current = SSL_PROTO_SSL;
+		else if (str_is_token(p, SSL_TXT_TLSV1, q - p))
+			current = SSL_PROTO_TLSv1;
+#ifdef SSL_OP_NO_TLSv1_1
+		else if (str_is_token(p, SSL_TXT_TLSV1_1, q - p))
+			current = SSL_PROTO_TLSv1_1;
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+		else if (str_is_token(p, SSL_TXT_TLSV1_2, q - p))
+			current = SSL_PROTO_TLSv1_2;
+#endif
+		else if (str_is_token(p, "TLS", q - p))
+			current = SSL_PROTO_TLS;
+		else
+			elog(FATAL, "invalid SSL protocol list");
+		switch (action) {
+		case '+':
+			result |= current;
+			break;
+		case '-':
+			result &= ~current;
+			break;
+		default:
+			result = current;
+			break;
+		}
+	}
+	/* forcibly disallow SSLv2 and SSLv3 */
+	if (result & SSL_PROTO_SSL) {
+		elog(WARNING, "removing SSLv2 and SSLv3 from SSL protocol list");
+		result &= ~SSL_PROTO_SSL;
+	}
+	/* check the result */
+	if (result == 0)
+		elog(FATAL, "could not set the protocol list (no valid protocols available)");
+	elog(DEBUG2, "enabling SSL protocols: %lx", result);
+	/* return the inverse */
+	return (SSL_PROTO_ALL & ~result);
+}
+
 #endif   /* USE_SSL */
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ea58cf6..3d1b668 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -125,6 +125,7 @@ extern char *default_tablespace;
 extern char *temp_tablespaces;
 extern bool ignore_checksum_failure;
 extern bool synchronize_seqscans;
+extern char *SSLProtocols;
 extern char *SSLCipherSuites;
 extern char *SSLECDHCurve;
 extern bool SSLPreferServerCiphers;
@@ -3215,6 +3216,21 @@ static struct config_string ConfigureNamesString[] =
 	},
 
 	{
+		{"ssl_protocols", PGC_POSTMASTER, CONN_AUTH_SECURITY,
+			gettext_noop("Sets the list of allowed SSL protocols."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&SSLProtocols,
+#ifdef USE_SSL
+		"ALL:-SSL",
+#else
+		"none",
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
 		{"ssl_ciphers", PGC_POSTMASTER, CONN_AUTH_SECURITY,
 			gettext_noop("Sets the list of allowed SSL ciphers."),
 			NULL,
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 8d5bb19..d161113 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -79,6 +79,7 @@
 
 #authentication_timeout = 1min		# 1s-600s
 #ssl = off				# (change requires restart)
+#ssl_protocols = 'ALL:-SSL'		# allowed SSL protocols
 #ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
 					# (change requires restart)
 #ssl_prefer_server_ciphers = on		# (change requires restart)