1 files changed, 89 insertions, 0 deletions
diff --git a/lib/libpam/modules/pam_self/pam_self.c b/lib/libpam/modules/pam_self/pam_self.c
new file mode 100644
index 000000000000..fceb6466d8fb
--- /dev/null
+++ b/lib/libpam/modules/pam_self/pam_self.c
@@ -0,0 +1,89 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2001 Mark R V Murray
+ * All rights reserved.
+ * Copyright (c) 2001,2002 Networks Associates Technology, Inc.
+ * All rights reserved.
+ *
+ * Portions of this software were developed for the FreeBSD Project by
+ * ThinkSec AS and NAI Labs, the Security Research Division of Network
+ * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
+ * ("CBOSS"), as part of the DARPA CHATS research program.
+ *
+ * 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 author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <sys/cdefs.h>
+#define _BSD_SOURCE
+
+#include <pwd.h>
+#include <unistd.h>
+#include <syslog.h>
+
+#define PAM_SM_AUTH
+
+#include <security/pam_appl.h>
+#include <security/pam_modules.h>
+#include <security/pam_mod_misc.h>
+
+#define OPT_ALLOW_ROOT "allow_root"
+
+PAM_EXTERN int
+pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
+    int argc __unused, const char *argv[] __unused)
+{
+	struct passwd *pwd;
+	const char *luser;
+	int pam_err;
+	uid_t uid;
+
+	pam_err = pam_get_user(pamh, &luser, NULL);
+	if (pam_err != PAM_SUCCESS)
+		return (pam_err);
+	if (luser == NULL || (pwd = getpwnam(luser)) == NULL)
+		return (PAM_AUTH_ERR);
+
+	uid = getuid();
+	if (uid == 0 && !openpam_get_option(pamh, OPT_ALLOW_ROOT))
+		return (PAM_AUTH_ERR);
+
+	if (uid == (uid_t)pwd->pw_uid)
+		return (PAM_SUCCESS);
+
+	PAM_VERBOSE_ERROR("Refused; source and target users differ");
+
+	return (PAM_AUTH_ERR);
+}
+
+PAM_EXTERN int
+pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
+    int argc __unused, const char *argv[] __unused)
+{
+
+	return (PAM_SUCCESS);
+}
+
+PAM_MODULE_ENTRY("pam_self");