auth: Add mechanism filter for passdbs

src/auth/auth-request.c

@@ -614,6 +614,16 @@ static bool
auth_request_want_skip_passdb(struct auth_request *request,
			      struct auth_passdb *passdb)
{
	/* if mechanism is not supported, skip */
	const char *const *mech = passdb->passdb->mechanisms;

	/* if request->mech == NULL it means we are doing
	   lookup without authentication and should not match this */
	if (mech != NULL && (request->mech == NULL ||
	     !str_array_icase_find(mech, request->mech->mech_name))) {
		return TRUE;
	}

	/* skip_password_check basically specifies if authentication is
	   finished */
	bool authenticated = request->skip_password_check;

src/auth/auth-settings.c

@@ -113,6 +113,7 @@ static const struct setting_define auth_passdb_setting_defines[] = {
	DEF(SET_STR, args),
	DEF(SET_STR, default_fields),
	DEF(SET_STR, override_fields),
	DEF(SET_STR, mechanisms),

	DEF(SET_ENUM, skip),
	DEF(SET_ENUM, result_success),
@@ -133,6 +134,7 @@ static const struct auth_passdb_settings auth_passdb_default_settings = {
	.args = "",
	.default_fields = "",
	.override_fields = "",
	.mechanisms = "",

	.skip = "never:authenticated:unauthenticated",
	.result_success = "return-ok:return:return-fail:continue:continue-ok:continue-fail",

src/auth/auth-settings.h

@@ -10,6 +10,7 @@ struct auth_passdb_settings {
	const char *args;
	const char *default_fields;
	const char *override_fields;
	const char *mechanisms;

	const char *skip;
	const char *result_success;

src/auth/passdb.c

@@ -223,6 +223,13 @@ passdb_preinit(pool_t pool, const struct auth_passdb_settings *set)
	passdb->id = ++auth_passdb_id;
	passdb->iface = *iface;
	passdb->args = p_strdup(pool, set->args);
	if (*set->mechanisms == '\0') {
		passdb->mechanisms = NULL;
	} else if (strcasecmp(set->mechanisms, "none") == 0) {
		passdb->mechanisms = (const char *const[]){NULL};
	} else {
		passdb->mechanisms = (const char* const*)p_strsplit_spaces(pool, set->mechanisms, " ,");
	}

	array_append(&passdb_modules, &passdb, 1);
	return passdb;

src/auth/passdb.h

@@ -62,6 +62,9 @@ struct passdb_module {
	/* Default password scheme for this module.
	   If cache_key is set, must not be NULL. */
	const char *default_pass_scheme;
	/* Supported authentication mechanisms, NULL is all, [NULL] is none*/
	const char *const *mechanisms;

	/* If blocking is set to TRUE, use child processes to access
	   this passdb. */
	bool blocking;