From cbb699a705d3f3d61fbb223d41e2a1c313c3609b Mon Sep 17 00:00:00 2001
From: Attila Molnar <attilamolnar@hush.com>
Date: Fri, 17 Oct 2014 18:46:47 +0200
Subject: m_ssl_openssl Add compile time option that allows disabling
 renegotiations

---
 src/modules/extra/m_ssl_openssl.cpp | 61 +++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/src/modules/extra/m_ssl_openssl.cpp b/src/modules/extra/m_ssl_openssl.cpp
index 737dab914..02f44f2f1 100644
--- a/src/modules/extra/m_ssl_openssl.cpp
+++ b/src/modules/extra/m_ssl_openssl.cpp
@@ -51,10 +51,16 @@
 /* $NoPedantic */
 
 
+class ModuleSSLOpenSSL;
+
 enum issl_status { ISSL_NONE, ISSL_HANDSHAKING, ISSL_OPEN };
 
 static bool SelfSigned = false;
 
+#ifdef INSPIRCD_OPENSSL_ENABLE_RENEGO_DETECTION
+static ModuleSSLOpenSSL* opensslmod = NULL;
+#endif
+
 char* get_error()
 {
 	return ERR_error_string(ERR_get_error(), NULL);
@@ -173,10 +179,40 @@ class ModuleSSLOpenSSL : public Module
 	}
 #endif
 
+#ifdef INSPIRCD_OPENSSL_ENABLE_RENEGO_DETECTION
+	static void SSLInfoCallback(const SSL* ssl, int where, int rc)
+	{
+		int fd = SSL_get_fd(const_cast<SSL*>(ssl));
+		issl_session& session = opensslmod->sessions[fd];
+
+		if ((where & SSL_CB_HANDSHAKE_START) && (session.status == ISSL_OPEN))
+		{
+			// The other side is trying to renegotiate, kill the connection and change status
+			// to ISSL_NONE so CheckRenego() closes the session
+			session.status = ISSL_NONE;
+			ServerInstance->SE->Shutdown(fd, 2);
+		}
+	}
+
+	bool CheckRenego(StreamSocket* sock, issl_session* session)
+	{
+		if (session->status != ISSL_NONE)
+			return true;
+
+		ServerInstance->Logs->Log("m_ssl_openssl", DEBUG, "Session %p killed, attempted to renegotiate", (void*)session->sess);
+		CloseSession(session);
+		sock->SetError("Renegotiation is not allowed");
+		return false;
+	}
+#endif
+
  public:
 
 	ModuleSSLOpenSSL() : iohook(this, "ssl/openssl", SERVICE_IOHOOK)
 	{
+#ifdef INSPIRCD_OPENSSL_ENABLE_RENEGO_DETECTION
+		opensslmod = this;
+#endif
 		sessions = new issl_session[ServerInstance->SE->GetMaxFds()];
 
 		/* Global SSL library initialization*/
@@ -235,6 +271,20 @@ class ModuleSSLOpenSSL : public Module
 
 		ConfigTag* Conf = ServerInstance->Config->ConfValue("openssl");
 
+#ifdef INSPIRCD_OPENSSL_ENABLE_RENEGO_DETECTION
+		// Set the callback if we are not allowing renegotiations, unset it if we do
+		if (Conf->getBool("renegotiation", true))
+		{
+			SSL_CTX_set_info_callback(ctx, NULL);
+			SSL_CTX_set_info_callback(clictx, NULL);
+		}
+		else
+		{
+			SSL_CTX_set_info_callback(ctx, SSLInfoCallback);
+			SSL_CTX_set_info_callback(clictx, SSLInfoCallback);
+		}
+#endif
+
 		if (Conf->getBool("showports", true))
 		{
 			sslports = Conf->getString("advertisedports");
@@ -533,6 +583,11 @@ class ModuleSSLOpenSSL : public Module
 			size_t bufsiz = ServerInstance->Config->NetBufferSize;
 			int ret = SSL_read(session->sess, buffer, bufsiz);
 
+#ifdef INSPIRCD_OPENSSL_ENABLE_RENEGO_DETECTION
+			if (!CheckRenego(user, session))
+				return -1;
+#endif
+
 			if (ret > 0)
 			{
 				recvq.append(buffer, ret);
@@ -601,6 +656,12 @@ class ModuleSSLOpenSSL : public Module
 		{
 			ERR_clear_error();
 			int ret = SSL_write(session->sess, buffer.data(), buffer.size());
+
+#ifdef INSPIRCD_OPENSSL_ENABLE_RENEGO_DETECTION
+			if (!CheckRenego(user, session))
+				return -1;
+#endif
+
 			if (ret == (int)buffer.length())
 			{
 				session->data_to_write = false;
-- 
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