EXT PW: Add framework for supporting external password storage

This new mechanism can be used to make wpa_supplicant using external
storage (e.g., key store in the operating system) for passwords,
passphrases, and PSKs. This commit is only adding the framework part
needed to support this, i.e., no actual configuration parameter can
yet use this new mechanism. In addition, only a simple test backend
is added to allow developer testing of the functionality.

Signed-hostap: Jouni Malinen <j@w1.fi>

src/utils/ext_password.c

@@ -0,0 +1,116 @@
+/*
+ * External password backend
+ * Copyright (c) 2012, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#ifdef __linux__
+#include <sys/mman.h>
+#endif /* __linux__ */
+
+#include "common.h"
+#include "ext_password_i.h"
+
+
+#ifdef CONFIG_EXT_PASSWORD_TEST
+extern struct ext_password_backend ext_password_test;
+#endif /* CONFIG_EXT_PASSWORD_TEST */
+
+static const struct ext_password_backend *backends[] = {
+#ifdef CONFIG_EXT_PASSWORD_TEST
+	&ext_password_test,
+#endif /* CONFIG_EXT_PASSWORD_TEST */
+	NULL
+};
+
+struct ext_password_data {
+	const struct ext_password_backend *backend;
+	void *priv;
+};
+
+
+struct ext_password_data * ext_password_init(const char *backend,
+					     const char *params)
+{
+	struct ext_password_data *data;
+	int i;
+
+	data = os_zalloc(sizeof(*data));
+	if (data == NULL)
+		return NULL;
+
+	for (i = 0; backends[i]; i++) {
+		if (os_strcmp(backends[i]->name, backend) == 0) {
+			data->backend = backends[i];
+			break;
+		}
+	}
+
+	if (!data->backend) {
+		os_free(data);
+		return NULL;
+	}
+
+	data->priv = data->backend->init(params);
+	if (data->priv == NULL) {
+		os_free(data);
+		return NULL;
+	}
+
+	return data;
+}
+
+
+void ext_password_deinit(struct ext_password_data *data)
+{
+	if (data && data->backend && data->priv)
+		data->backend->deinit(data->priv);
+	os_free(data);
+}
+
+
+struct wpabuf * ext_password_get(struct ext_password_data *data,
+				 const char *name)
+{
+	if (data == NULL)
+		return NULL;
+	return data->backend->get(data->priv, name);
+}
+
+
+struct wpabuf * ext_password_alloc(size_t len)
+{
+	struct wpabuf *buf;
+
+	buf = wpabuf_alloc(len);
+	if (buf == NULL)
+		return NULL;
+
+#ifdef __linux__
+	if (mlock(wpabuf_head(buf), wpabuf_len(buf)) < 0) {
+		wpa_printf(MSG_ERROR, "EXT PW: mlock failed: %s",
+			   strerror(errno));
+	}
+#endif /* __linux__ */
+
+	return buf;
+}
+
+
+void ext_password_free(struct wpabuf *pw)
+{
+	if (pw == NULL)
+		return;
+	os_memset(wpabuf_mhead(pw), 0, wpabuf_len(pw));
+#ifdef __linux__
+	if (munlock(wpabuf_head(pw), wpabuf_len(pw)) < 0) {
+		wpa_printf(MSG_ERROR, "EXT PW: munlock failed: %s",
+			   strerror(errno));
+	}
+#endif /* __linux__ */
+	wpabuf_free(pw);
+}