transport: refactor protocol whitelist code

diff --git a/transport.c b/transport.c
index 88bde1d85e48e7866881806d1ec3f1e3d420ab67..647d2c2afaadb4f39dd74b182db969eaf0623aa0 100644 (file)
--- a/transport.c
+++ b/transport.c
@@ -909,6 +909,42 @@ static int external_specification_len(const char *url)
        return strchr(url, ':') - url;
 }
 
+static const struct string_list *protocol_whitelist(void)
+{
+       static int enabled = -1;
+       static struct string_list allowed = STRING_LIST_INIT_DUP;
+
+       if (enabled < 0) {
+               const char *v = getenv("GIT_ALLOW_PROTOCOL");
+               if (v) {
+                       string_list_split(&allowed, v, ':', -1);
+                       string_list_sort(&allowed);
+                       enabled = 1;
+               } else {
+                       enabled = 0;
+               }
+       }
+
+       return enabled ? &allowed : NULL;
+}
+
+int is_transport_allowed(const char *type)
+{
+       const struct string_list *allowed = protocol_whitelist();
+       return !allowed || string_list_has_string(allowed, type);
+}
+
+void transport_check_allowed(const char *type)
+{
+       if (!is_transport_allowed(type))
+               die("transport '%s' not allowed", type);
+}
+
+int transport_restrict_protocols(void)
+{
+       return !!protocol_whitelist();
+}
+
 struct transport *transport_get(struct remote *remote, const char *url)
 {
        const char *helper;
@@ -940,12 +976,14 @@ struct transport *transport_get(struct remote *remote, const char *url)
        if (helper) {
                transport_helper_init(ret, helper);
        } else if (starts_with(url, "rsync:")) {
+               transport_check_allowed("rsync");
                ret->get_refs_list = get_refs_via_rsync;
                ret->fetch = fetch_objs_via_rsync;
                ret->push = rsync_transport_push;
                ret->smart_options = NULL;
        } else if (url_is_local_not_ssh(url) && is_file(url) && is_bundle(url, 1)) {
                struct bundle_transport_data *data = xcalloc(1, sizeof(*data));
+               transport_check_allowed("file");
                ret->data = data;
                ret->get_refs_list = get_refs_from_bundle;
                ret->fetch = fetch_refs_from_bundle;
@@ -957,7 +995,10 @@ struct transport *transport_get(struct remote *remote, const char *url)
                || starts_with(url, "ssh://")
                || starts_with(url, "git+ssh://")
                || starts_with(url, "ssh+git://")) {
-               /* These are builtin smart transports. */
+               /*
+                * These are builtin smart transports; "allowed" transports
+                * will be checked individually in git_connect.
+                */
                struct git_transport_data *data = xcalloc(1, sizeof(*data));
                ret->data = data;
                ret->set_option = NULL;