1 files changed, 109 insertions, 0 deletions
diff --git a/lib/console.c b/lib/console.c
new file mode 100644
index 0000000..92065d9
--- /dev/null
+++ b/lib/console.c
@@ -0,0 +1,109 @@
+/*
+ * SPDX-FileCopyrightText: 1991       , Julianne Frances Haugh
+ * SPDX-FileCopyrightText: 1991       , Chip Rosenthal
+ * SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
+ * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
+ * SPDX-FileCopyrightText: 2007 - 2010, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+#include "defines.h"
+#include <stdio.h>
+#include "getdef.h"
+#include "prototypes.h"
+#include "string/strtcpy.h"
+
+#ident "$Id$"
+
+/*
+ * This is now rather generic function which decides if "tty" is listed
+ * under "cfgin" in config (directly or indirectly). Fallback to default if
+ * something is bad.
+ */
+static bool is_listed (const char *cfgin, const char *tty, bool def)
+{
+	FILE *fp;
+	char buf[1024], *s;
+	const char *cons;
+
+	/*
+	 * If the CONSOLE configuration definition isn't given,
+	 * fallback to default.
+	 */
+
+	cons = getdef_str (cfgin);
+	if (NULL == cons) {
+		return def;
+	}
+
+	/*
+	 * If this isn't a filename, then it is a ":" delimited list of
+	 * console devices upon which root logins are allowed.
+	 */
+
+	if (*cons != '/') {
+		char *pbuf;
+		STRTCPY(buf, cons);
+		pbuf = &buf[0];
+		while ((s = strtok (pbuf, ":")) != NULL) {
+			if (strcmp (s, tty) == 0) {
+				return true;
+			}
+
+			pbuf = NULL;
+		}
+		return false;
+	}
+
+	/*
+	 * If we can't open the console list, then call everything a
+	 * console - otherwise root will never be allowed to login.
+	 */
+
+	fp = fopen (cons, "r");
+	if (NULL == fp) {
+		return def;
+	}
+
+	/*
+	 * See if this tty is listed in the console file.
+	 */
+
+	while (fgets (buf, sizeof (buf), fp) != NULL) {
+		/* Remove optional trailing '\n'. */
+		buf[strcspn (buf, "\n")] = '\0';
+		if (strcmp (buf, tty) == 0) {
+			(void) fclose (fp);
+			return true;
+		}
+	}
+
+	/*
+	 * This tty isn't a console.
+	 */
+
+	(void) fclose (fp);
+	return false;
+}
+
+/*
+ * console - return 1 if the "tty" is a console device, else 0.
+ *
+ * Note - we need to take extreme care here to avoid locking out root logins
+ * if something goes awry.  That's why we do things like call everything a
+ * console if the consoles file can't be opened.  Because of this, we must
+ * warn the user to protect against the remove of the consoles file since
+ * that would allow an unauthorized root login.
+ */
+
+bool console (const char *tty)
+{
+	if (strncmp (tty, "/dev/", 5) == 0) {
+		tty += 5;
+	}
+
+	return is_listed ("CONSOLE", tty, true);
+}
+