1 files changed, 120 insertions, 0 deletions
diff --git a/lib/chkname.c b/lib/chkname.c
new file mode 100644
index 0000000..995562f
--- /dev/null
+++ b/lib/chkname.c
@@ -0,0 +1,120 @@
+// SPDX-FileCopyrightText: 1990-1994, Julianne Frances Haugh
+// SPDX-FileCopyrightText: 1996-2000, Marek Michałkiewicz
+// SPDX-FileCopyrightText: 2001-2005, Tomasz Kłoczko
+// SPDX-FileCopyrightText: 2005-2008, Nicolas François
+// SPDX-FileCopyrightText: 2023-2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+/*
+ * is_valid_user_name(), is_valid_group_name() - check the new user/group
+ * name for validity;
+ * return values:
+ *   true  - OK
+ *   false - bad name
+ */
+
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <unistd.h>
+
+#include "defines.h"
+#include "chkname.h"
+
+
+int allow_bad_names = false;
+
+
+size_t
+login_name_max_size(void)
+{
+	long  conf;
+
+	errno = 0;
+	conf = sysconf(_SC_LOGIN_NAME_MAX);
+	if (conf == -1 && errno != 0)
+		return LOGIN_NAME_MAX;
+
+	return conf;
+}
+
+
+static bool is_valid_name (const char *name)
+{
+	if (allow_bad_names) {
+		return true;
+	}
+
+	/*
+         * User/group names must match BRE regex:
+         *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
+         *
+         * as a non-POSIX, extension, allow "$" as the last char for
+         * sake of Samba 3.x "add machine script"
+         *
+         * Also do not allow fully numeric names or just "." or "..".
+         */
+	int numeric;
+
+	if ('\0' == *name ||
+	    ('.' == *name && (('.' == name[1] && '\0' == name[2]) ||
+			      '\0' == name[1])) ||
+	    !((*name >= 'a' && *name <= 'z') ||
+	      (*name >= 'A' && *name <= 'Z') ||
+	      (*name >= '0' && *name <= '9') ||
+	      *name == '_' ||
+	      *name == '.')) {
+		return false;
+	}
+
+	numeric = isdigit(*name);
+
+	while ('\0' != *++name) {
+		if (!((*name >= 'a' && *name <= 'z') ||
+		      (*name >= 'A' && *name <= 'Z') ||
+		      (*name >= '0' && *name <= '9') ||
+		      *name == '_' ||
+		      *name == '.' ||
+		      *name == '-' ||
+		      (*name == '$' && name[1] == '\0')
+		     )) {
+			return false;
+		}
+		numeric &= isdigit(*name);
+	}
+
+	return !numeric;
+}
+
+
+bool
+is_valid_user_name(const char *name)
+{
+	if (strlen(name) >= login_name_max_size())
+		return false;
+
+	return is_valid_name(name);
+}
+
+
+bool is_valid_group_name (const char *name)
+{
+	/*
+	 * Arbitrary limit for group names.
+	 * HP-UX 10 limits to 16 characters
+	 */
+	if (   (GROUP_NAME_MAX_LENGTH > 0)
+	    && (strlen (name) > GROUP_NAME_MAX_LENGTH)) {
+		return false;
+	}
+
+	return is_valid_name (name);
+}