CVE-2022-3287 (C, published 2022-09-28T20:15Z)
Description: value: When creating an OPERATOR user account on the BMC, the redfish plugin saved the auto-generated password to /etc/fwupd/redfish.conf without proper restriction, allowing any user on the system to read the same configuration file.
Severity: nan (CVSS v3 base score: 6.5)
Weakness: CWE-552 \u2014 Files or Directories Accessible to External Parties
The product makes files or directories accessible to unauthorized actors, even though they should not be.
Repository: https://github.com/fwupd/fwupd
Files changed:
contrib/fwupd.spec.in
libfwupdplugin/fu-plugin.c
libfwupdplugin/fu-self-test.c
Commit message: Never save the Redfish passwords to a file readable by users

When the redfish plugin automatically creates an OPERATOR user account on the
BMC we save the autogenerated password to /etc/fwupd/redfish.conf, ensuring it
is chmod'ed to 0660 before writing the file with g_key_file_save_to_file().

Under the covers, g_key_file_save_to_file() calls g_file_set_contents() with
the keyfile string data.
I was under the impression that G_FILE_CREATE_REPLACE_DESTINATION was being
used to copy permissions, but alas not.

GLib instead calls g_file_set_contents_full() with the mode hardcoded to 0666,
which undoes the previous chmod().

Use g_file_set_contents_full() with the correct mode for newer GLib versions,
and provide a fallback with the same semantics for older versions.


Vulnerable code:
	gint ret;
	ret = g_chmod(conf_path, 0660);
	if (ret == -1) {
		g_set_error(error,
			    FWUPD_ERROR,
			    FWUPD_ERROR_INTERNAL,
			    "failed to set permissions on %s",
			    conf_path);
	}

	return fu_plugin_set_config_value(self, key, value, error);

Fixed code:
# ensure this is private
chmod 0660 /etc/fwupd/redfish.conf

#include <fcntl.h>
#if !GLIB_CHECK_VERSION(2, 66, 0)

#define G_FILE_SET_CONTENTS_CONSISTENT 0
typedef guint GFileSetContentsFlags;
static gboolean
g_file_set_contents_full(const gchar *filename,
			 const gchar *contents,
			 gssize length,
			 GFileSetContentsFlags flags,
			 int mode,
			 GError **error)
{
	gint fd;
	gssize wrote;

	if (length < 0)
		length = strlen(contents);
	fd = g_open(filename, O_CREAT, mode);
	if (fd <= 0) {
		g_set_error(error,
			    G_IO_ERROR,
			    G_IO_ERROR_FAILED,
			    "could not open %s file",
			    filename);
		return FALSE;
	}
	wrote = write(fd, contents, length);
	if (wrote != length) {
		g_set_error(error,
			    G_IO_ERROR,
			    G_IO_ERROR_FAILED,
			    "did not write %s file",
			    filename);
		g_close(fd, NULL);
		return FALSE;
	}
	return g_close(fd, error);
}
#endif

	g_autofree gchar *data = NULL;
	g_autoptr(GKeyFile) keyfile = g_key_file_new();
	if (!g_key_file_load_from_file(keyfile, conf_path, G_KEY_FILE_KEEP_COMMENTS, error))
	g_key_file_set_string(keyfile, fu_plugin_get_name(self), key, value);
	data = g_key_file_to_data(keyfile, NULL, error);
	if (data == NULL)
		return FALSE;
	return g_file_set_contents_full(conf_path,
					data,
					-1,
					G_FILE_SET_CONTENTS_CONSISTENT,
					0660,
					error);
static void
fu_plugin_config_func(void)
{
	GStatBuf statbuf = {0};
	gboolean ret;
	gint rc;
	g_autofree gchar *conf_dir = NULL;
	g_autofree gchar *conf_file = NULL;
	g_autofree gchar *fn = NULL;
	g_autofree gchar *testdatadir = NULL;
	g_autofree gchar *value = NULL;
	g_autoptr(FuPlugin) plugin = fu_plugin_new(NULL);
	g_autoptr(GError) error = NULL;

	/* this is a build file */
	testdatadir = g_test_build_filename(G_TEST_BUILT, "tests", NULL);
	(void)g_setenv("FWUPD_SYSCONFDIR", testdatadir, TRUE);
	conf_dir = fu_path_from_kind(FU_PATH_KIND_SYSCONFDIR_PKG);

	/* remove existing file */
	fu_plugin_set_name(plugin, "test");
	conf_file = g_strdup_printf("%s.conf", fu_plugin_get_name(plugin));
	fn = g_build_filename(conf_dir, conf_file, NULL);
	ret = fu_path_mkdir_parent(fn, &error);
	g_assert_no_error(error);
	g_assert_true(ret);
	g_remove(fn);
	ret = g_file_set_contents(fn, "", -1, &error);
	g_assert_no_error(error);
	g_assert_true(ret);

	/* set a value */
	ret = fu_plugin_set_config_value(plugin, "Key", "True", &error);
	g_assert_no_error(error);
	g_assert_true(ret);
	g_assert_true(g_file_test(fn, G_FILE_TEST_EXISTS));

	/* check it is world readable */
	rc = g_stat(fn, &statbuf);
	g_assert_cmpint(rc, ==, 0);
	g_assert_cmpint(statbuf.st_mode & 0777, ==, 0644);

	/* read back the value */
	value = fu_plugin_get_config_value(plugin, "Key");
	g_assert_cmpstr(value, ==, "True");
	g_assert_true(fu_plugin_get_config_value_boolean(plugin, "Key"));

	/* check it is private, i.e. only readable by the user/group */
	ret = fu_plugin_set_secure_config_value(plugin, "Key", "False", &error);
	g_assert_no_error(error);
	g_assert_true(ret);
	rc = g_stat(fn, &statbuf);
	g_assert_cmpint(rc, ==, 0);
	g_assert_cmpint(statbuf.st_mode & 0777, ==, 0640);
}

	g_test_add_func("/fwupd/plugin{config}", fu_plugin_config_func);