Also reload SSL context on bip reload, allowing for SSL cert updates

- on BIP reload, check if SSL files are readable, and try to load new
  SSL context.
- on success only, update SSL context for new client connections

This allows for SSL certificate/key updates on /BIP reload or SIGHUP.

Signed-off-by: Loïc Gomez <bip@animanova.fr>

src/bip_main.c

@@ -68,6 +68,7 @@ void rlimit_cpu_reached(int i);
 void rlimit_bigfile_reached(int i);
 void conf_die(bip_t *bip, char *fmt, ...);
 int fireup(bip_t *bip, FILE *conf);
+int check_ssl_files(int failmode);
 int do_pid_stuff(void);
 
 static void usage(char *name)
@@ -143,6 +144,44 @@ static pid_t daemonize(void)
 	return getpid();
 }
 
+int check_ssl_files(int failmode)
+{
+	int e;
+	struct stat fs;
+
+	if (!conf_ssl_certfile) {
+		conf_ssl_certfile = default_path(
+			conf_biphome, "bip.pem", "SSL certificate");
+	}
+
+	if (failmode == HARD_FAIL)
+		assert_path_exists(conf_ssl_certfile);
+	else if (!check_path_exists(conf_ssl_certfile))
+		return 0;
+
+	e = stat(conf_ssl_certfile, &fs);
+	if (e)
+		mylog(LOG_WARN,
+			  "Unable to check PEM file, stat(%s): %s",
+			  conf_ssl_certfile, strerror(errno));
+	else if ((fs.st_mode & S_IROTH) | (fs.st_mode & S_IWOTH))
+		mylog(LOG_ERROR,
+			  "PEM file %s should not be world "
+			  "readable / writable. Please fix the modes.",
+			  conf_ssl_certfile);
+
+	if (conf_client_dh_file) {
+		if (failmode == HARD_FAIL) {
+			assert_path_exists(conf_client_dh_file);
+		} else if (!check_path_exists(conf_client_dh_file)) {
+			return 0;
+		}
+	}
+
+	/* all is well */
+	return 1;
+}
+
 int main(int argc, char **argv)
 {
 	FILE *conf = NULL;
@@ -264,31 +303,8 @@ int main(int argc, char **argv)
 
 #ifdef HAVE_LIBSSL
 	if (conf_css) {
-		int e;
-		struct stat fs;
-
-		if (!conf_ssl_certfile) {
-			conf_ssl_certfile = default_path(
-				conf_biphome, "bip.pem", "SSL certificate");
-		}
-		assert_path_exists(conf_ssl_certfile);
-
-		e = stat(conf_ssl_certfile, &fs);
-		if (e)
-			mylog(LOG_WARN,
-			      "Unable to check PEM file, stat(%s): "
-			      "%s",
-			      conf_ssl_certfile, strerror(errno));
-		else if ((fs.st_mode & S_IROTH) | (fs.st_mode & S_IWOTH))
-			mylog(LOG_ERROR,
-			      "PEM file %s should not be world "
-			      "readable / writable. Please fix the modes.",
-			      conf_ssl_certfile);
-
-		if (conf_client_dh_file) {
-			assert_path_exists(conf_client_dh_file);
-		}
-	}
+        check_ssl_files(HARD_FAIL);
+    }
 #endif
 
 	check_dir(conf_log_root, 1);
@@ -324,6 +340,24 @@ int main(int argc, char **argv)
 
 		/* re-open to allow logfile rotate */
 		log_file_setup();
+
+#ifdef HAVE_LIBSSL
+		/*
+         * reload SSL context if server-side SSL is enabled and SSL files
+		 * seem accessible.
+         */
+		if (conf_css) {
+			if (check_ssl_files(SOFT_FAIL)) {
+				if (set_ssl_context(SSLCTX_FORCE_UPDATE) == 1)
+				    mylog(LOG_DEBUG, "SSL context has been updated");
+                else
+				    mylog(LOG_DEBUG, "SSL context has not been updated");
+            } else {
+				mylog(LOG_ERROR, "Unable to update SSL context, "
+								"file checks failed");
+            }
+		}
+#endif
 	}
 	return 1;
 }

src/connection.c

@@ -34,6 +34,7 @@ extern char *conf_client_ciphers;
 extern char *conf_client_dh_file;
 static int SSLize(connection_t *cn, int *nc);
 static SSL_CTX *SSL_init_context(char *ciphers);
+SSL_CTX *get_ssl_context(void);
 /* SSH like trust management */
 int link_add_untrusted(void *ls, X509 *cert);
 #endif
@@ -1231,6 +1232,77 @@ static int ctx_set_dh(SSL_CTX *ctx)
             conf_client_dh_file);
 	return 1;
 }
+
+int set_ssl_context(int force)
+{
+	SSL_CTX *newctx = NULL;
+	if (sslctx) {
+		if (force == SSLCTX_FORCE_UPDATE) {
+			mylog(LOG_DEBUG, "SSL context already set, forcing update");
+		} else {
+			mylog(LOG_DEBUG, "SSL context is already set, not updating");
+			return 0;
+		}
+	} else {
+		mylog(LOG_DEBUG, "Initializing SSL context for accepted connections");
+	}
+
+	newctx = get_ssl_context();
+	if (!newctx) {
+		mylog(LOG_ERROR, "Failed to get new SSL context");
+		if (sslctx)
+			mylog(LOG_WARN, "Keeping old SSL context");
+		return 0;
+	}
+	sslctx = newctx;
+	return 1;
+}
+
+SSL_CTX *get_ssl_context(void)
+{
+	SSL_CTX *newctx = NULL;
+	if (!(newctx = SSL_init_context(conf_client_ciphers))) {
+		mylog(LOG_ERROR, "SSL context initialization failed");
+		return NULL;
+	}
+
+	if (!conf_client_dh_file) {
+		// try with a default path but don't fail if it doesn't exist
+		conf_client_dh_file = default_path(conf_biphome, "dh.pem",
+					 "DH parameters");
+
+		struct stat st_buf;
+		if (stat(conf_client_dh_file, &st_buf) != 0) {
+			free(conf_client_dh_file);
+			conf_client_dh_file = NULL;
+		}
+	}
+
+	if (conf_client_dh_file) {
+		if (!ctx_set_dh(newctx)) {
+			SSL_CTX_free(newctx);
+			mylog(LOG_ERROR, "SSL Unable to load DH parameters");
+			return NULL;
+		}
+	}
+
+	mylog(LOG_DEBUG, "Loading SSL cert from %s", conf_ssl_certfile);
+	if (!SSL_CTX_use_certificate_chain_file(newctx, conf_ssl_certfile)) {
+		mylog(LOG_WARN, "SSL: Unable to load certificate file");
+		SSL_CTX_free(newctx);
+		return NULL;
+	}
+
+	mylog(LOG_DEBUG, "Loading SSL key from %s", conf_ssl_certfile);
+	if (!SSL_CTX_use_PrivateKey_file(newctx, conf_ssl_certfile,
+					 SSL_FILETYPE_PEM)) {
+		mylog(LOG_WARN, "SSL: Unable to load key file");
+		SSL_CTX_free(newctx);
+		return NULL;
+	}
+
+	return newctx;
+}
 #endif
 
 connection_t *accept_new(connection_t *cn)
@@ -1266,52 +1338,11 @@ connection_t *accept_new(connection_t *cn)
 	conn->client = 1;
 #ifdef HAVE_LIBSSL
 	if (cn->ssl) {
+		if (!sslctx)
+			set_ssl_context(SSLCTX_NO_REPLACE);
 		if (!sslctx) {
-			mylog(LOG_DEBUG,
-			      "No SSL context available for "
-			      "accepted connections. "
-			      "Initializing...");
-			if (!(sslctx = SSL_init_context(conf_client_ciphers))) {
-				mylog(LOG_ERROR,
-				      "SSL context initialization "
-				      "failed");
-				connection_free(conn);
-				return NULL;
-			}
-
-			if (!conf_client_dh_file) {
-				// try with a default path but don't fail if it
-				// doesn't exist
-				conf_client_dh_file =
-					default_path(conf_biphome, "dh.pem",
-						     "DH parameters");
-
-				struct stat st_buf;
-				if (stat(conf_client_dh_file, &st_buf) != 0) {
-					free(conf_client_dh_file);
-					conf_client_dh_file = NULL;
-				}
-			}
-
-			if (conf_client_dh_file) {
-				if (!ctx_set_dh(sslctx)) {
-					mylog(LOG_ERROR,
-					      "SSL Unable to load DH "
-					      "parameters");
-					connection_free(conn);
-					return NULL;
-				}
-			}
-
-			if (!SSL_CTX_use_certificate_chain_file(
-				    sslctx, conf_ssl_certfile))
-				mylog(LOG_WARN,
-				      "SSL: Unable to load "
-				      "certificate file");
-			if (!SSL_CTX_use_PrivateKey_file(sslctx,
-							 conf_ssl_certfile,
-							 SSL_FILETYPE_PEM))
-				mylog(LOG_WARN, "SSL: Unable to load key file");
+			connection_free(conn);
+			return NULL;
 		}
 
 		conn->ssl_h = SSL_new(sslctx);

src/connection.h

@@ -60,6 +60,9 @@
 #define SSL_CHECK_NONE (0)
 #define SSL_CHECK_BASIC (1)
 #define SSL_CHECK_CA (2)
+
+#define SSLCTX_NO_REPLACE 0
+#define SSLCTX_FORCE_UPDATE 1
 #endif
 
 struct connecting_data;
@@ -113,4 +116,9 @@ uint16_t connection_localport(connection_t *cn);
 uint16_t connection_remoteport(connection_t *cn);
 char *connection_localip(connection_t *cn);
 char *connection_remoteip(connection_t *cn);
+#ifdef HAVE_LIBSSL
+/* Set SSL context, force update if already set and force is 1
+ * Return 1 if SSL context has been set */
+int set_ssl_context(int force);
+#endif
 #endif

src/path_util.c

@@ -35,3 +35,15 @@ void assert_path_exists(char *path)
 	if (stat(path, &st_buf) != 0)
 		fatal("Path %s doesn't exist (%s)", path, strerror(errno));
 }
+
+int check_path_exists(char *path)
+{
+	struct stat st_buf;
+
+	if (stat(path, &st_buf) != 0) {
+		mylog(LOG_WARN, "Path %s doesn't exist (%s)", path, strerror(errno));
+        return 0;
+    } else {
+        return 1;
+    }
+}

src/path_util.h

@@ -18,5 +18,7 @@
 char *default_path(const char *biphome, const char *filename, const char *desc);
 /* exit program if path doesn't exist */
 void assert_path_exists(char *path);
+/* return 1 if path exists, 0 otherwise */
+int check_path_exists(char *path);
 
 #endif