1 files changed, 124 insertions, 0 deletions
diff --git a/libmisc/root_flag.c b/libmisc/root_flag.c
new file mode 100644
index 0000000..7f5e611
--- /dev/null
+++ b/libmisc/root_flag.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2011       , Julian Pidancet
+ * Copyright (c) 2011       , Nicolas François
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the copyright holders or contributors may not be used to
+ *    endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <stdio.h>
+#include <assert.h>
+#include "defines.h"
+#include "prototypes.h"
+/*@-exitarg@*/
+#include "exitcodes.h"
+
+static void change_root (const char* newroot);
+
+/*
+ * process_root_flag - chroot if given the --root option
+ *
+ * This shall be called before accessing the passwd, group, shadow,
+ * gshadow, useradd's default, login.defs files (non exhaustive list)
+ * or authenticating the caller.
+ *
+ * The audit, syslog, or locale files shall be open before
+ */
+extern void process_root_flag (const char* short_opt, int argc, char **argv)
+{
+	/*
+	 * Parse the command line options.
+	 */
+	int i;
+	const char *newroot = NULL;
+
+	for (i = 0; i < argc; i++) {
+		if (   (strcmp (argv[i], "--root") == 0)
+		    || (strcmp (argv[i], short_opt) == 0)) {
+			if (NULL != newroot) {
+				fprintf (stderr,
+				         _("%s: multiple --root options\n"),
+				         Prog);
+				exit (E_BAD_ARG);
+			}
+
+			if (i + 1 == argc) {
+				fprintf (stderr,
+				         _("%s: option '%s' requires an argument\n"),
+				         Prog, argv[i]);
+				exit (E_BAD_ARG);
+			}
+			newroot = argv[i + 1];
+		}
+	}
+
+	if (NULL != newroot) {
+		change_root (newroot);
+	}
+}
+
+static void change_root (const char* newroot)
+{
+	/* Drop privileges */
+	if (   (setregid (getgid (), getgid ()) != 0)
+	    || (setreuid (getuid (), getuid ()) != 0)) {
+		fprintf (stderr, _("%s: failed to drop privileges (%s)\n"),
+		         Prog, strerror (errno));
+		exit (EXIT_FAILURE);
+	}
+
+	if ('/' != newroot[0]) {
+		fprintf (stderr,
+		         _("%s: invalid chroot path '%s'\n"),
+		         Prog, newroot);
+		exit (E_BAD_ARG);
+	}
+
+	if (access (newroot, F_OK) != 0) {
+		fprintf(stderr,
+		        _("%s: cannot access chroot directory %s: %s\n"),
+		        Prog, newroot, strerror (errno));
+		exit (E_BAD_ARG);
+	}
+
+	if (chdir (newroot) != 0) {
+		fprintf(stderr,
+				_("%s: cannot chdir to chroot directory %s: %s\n"),
+				Prog, newroot, strerror (errno));
+		exit (E_BAD_ARG);
+	}
+
+	if (chroot (newroot) != 0) {
+		fprintf(stderr,
+		        _("%s: unable to chroot to directory %s: %s\n"),
+		        Prog, newroot, strerror (errno));
+		exit (E_BAD_ARG);
+	}
+}
+