1 files changed, 139 insertions, 0 deletions
diff --git a/src/home/home-util.c b/src/home/home-util.c
new file mode 100644
index 0000000..c777d7b
--- /dev/null
+++ b/src/home/home-util.c
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "dns-domain.h"
+#include "home-util.h"
+#include "libcrypt-util.h"
+#include "memory-util.h"
+#include "path-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "user-util.h"
+
+bool suitable_user_name(const char *name) {
+
+        /* Checks whether the specified name is suitable for management via homed. Note that client-side
+         * we usually validate with the simple valid_user_group_name(), while server-side we are a bit more
+         * restrictive, so that we can change the rules server-side without having to update things
+         * client-side too. */
+
+        if (!valid_user_group_name(name, 0))
+                return false;
+
+        /* We generally rely on NSS to tell us which users not to care for, but let's filter out some
+         * particularly well-known users. */
+        if (STR_IN_SET(name,
+                       "root",
+                       "nobody",
+                       NOBODY_USER_NAME, NOBODY_GROUP_NAME))
+                return false;
+
+        /* Let's also defend our own namespace, as well as Debian's (unwritten?) logic of prefixing system
+         * users with underscores. */
+        if (STARTSWITH_SET(name, "systemd-", "_"))
+                return false;
+
+        return true;
+}
+
+int suitable_realm(const char *realm) {
+        _cleanup_free_ char *normalized = NULL;
+        int r;
+
+        /* Similar to the above: let's validate the realm a bit stricter server-side than client side */
+
+        r = dns_name_normalize(realm, 0, &normalized); /* this also checks general validity */
+        if (r == -EINVAL)
+                return 0;
+        if (r < 0)
+                return r;
+
+        if (!streq(realm, normalized)) /* is this normalized? */
+                return false;
+
+        if (dns_name_is_root(realm)) /* Don't allow top level domain */
+                return false;
+
+        return true;
+}
+
+int suitable_image_path(const char *path) {
+
+        return !empty_or_root(path) &&
+                path_is_valid(path) &&
+                path_is_absolute(path);
+}
+
+bool supported_fstype(const char *fstype) {
+        /* Limit the set of supported file systems a bit, as protection against little tested kernel file
+         * systems. Also, we only support the resize ioctls for these file systems. */
+        return STR_IN_SET(fstype, "ext4", "btrfs", "xfs");
+}
+
+int split_user_name_realm(const char *t, char **ret_user_name, char **ret_realm) {
+        _cleanup_free_ char *user_name = NULL, *realm = NULL;
+        const char *c;
+        int r;
+
+        assert(t);
+        assert(ret_user_name);
+        assert(ret_realm);
+
+        c = strchr(t, '@');
+        if (!c) {
+                user_name = strdup(t);
+                if (!user_name)
+                        return -ENOMEM;
+        } else {
+                user_name = strndup(t, c - t);
+                if (!user_name)
+                        return -ENOMEM;
+
+                realm = strdup(c + 1);
+                if (!realm)
+                        return -ENOMEM;
+        }
+
+        if (!suitable_user_name(user_name))
+                return -EINVAL;
+
+        if (realm) {
+                r = suitable_realm(realm);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return -EINVAL;
+        }
+
+        *ret_user_name = TAKE_PTR(user_name);
+        *ret_realm = TAKE_PTR(realm);
+
+        return 0;
+}
+
+int bus_message_append_secret(sd_bus_message *m, UserRecord *secret) {
+        _cleanup_(erase_and_freep) char *formatted = NULL;
+        JsonVariant *v;
+        int r;
+
+        assert(m);
+        assert(secret);
+
+        if (!FLAGS_SET(secret->mask, USER_RECORD_SECRET))
+                return sd_bus_message_append(m, "s", "{}");
+
+        v = json_variant_by_key(secret->json, "secret");
+        if (!v)
+                return -EINVAL;
+
+        r = json_variant_format(v, 0, &formatted);
+        if (r < 0)
+                return r;
+
+        (void) sd_bus_message_sensitive(m);
+
+        return sd_bus_message_append(m, "s", formatted);
+}
+
+const char *home_record_dir(void) {
+        return secure_getenv("SYSTEMD_HOME_RECORD_DIR") ?: "/var/lib/systemd/home/";
+}