1 files changed, 208 insertions, 0 deletions
diff --git a/modules/pam_localuser/pam_localuser.c b/modules/pam_localuser/pam_localuser.c
new file mode 100644
index 00000000..cb507524
--- /dev/null
+++ b/modules/pam_localuser/pam_localuser.c
@@ -0,0 +1,208 @@
+/*
+ * pam_localuser module
+ *
+ * Copyright 2001, 2004 Red Hat, Inc.
+ * Copyright (c) 2020 Dmitry V. Levin <ldv@altlinux.org>
+ *
+ * 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, and the entire permission notice in its entirety,
+ *    including the disclaimer of warranties.
+ * 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.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions.  (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 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"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include <unistd.h>
+
+#include <security/pam_modules.h>
+#include <security/pam_ext.h>
+#include "pam_inline.h"
+
+static int
+check_user_in_passwd(pam_handle_t *pamh, const char *user_name,
+		     const char *file_name)
+{
+	int rc;
+	size_t user_len;
+	FILE *fp;
+	char line[BUFSIZ];
+
+	/* Validate the user name.  */
+	if ((user_len = strlen(user_name)) == 0) {
+		pam_syslog(pamh, LOG_NOTICE, "user name is not valid");
+		return PAM_SERVICE_ERR;
+	}
+
+	if (user_len > sizeof(line) - sizeof(":")) {
+		pam_syslog(pamh, LOG_NOTICE, "user name is too long");
+		return PAM_SERVICE_ERR;
+	}
+
+	if (strchr(user_name, ':') != NULL) {
+		/*
+		 * "root:x" is not a local user name even if the passwd file
+		 * contains a line starting with "root:x:".
+		 */
+		return PAM_PERM_DENIED;
+	}
+
+	/* Open the passwd file.  */
+	if (file_name == NULL) {
+		file_name = "/etc/passwd";
+	}
+	if ((fp = fopen(file_name, "r")) == NULL) {
+		pam_syslog(pamh, LOG_ERR, "error opening %s: %m", file_name);
+		return PAM_SERVICE_ERR;
+	}
+
+	/*
+	 * Scan the file using fgets() instead of fgetpwent_r() because
+	 * the latter is not flexible enough in handling long lines
+	 * in passwd files.
+	 */
+	rc = PAM_PERM_DENIED;
+	while (fgets(line, sizeof(line), fp) != NULL) {
+		size_t line_len;
+		const char *str;
+
+		/*
+		 * Does this line start with the user name
+		 * followed by a colon?
+		 */
+		if (strncmp(user_name, line, user_len) == 0 &&
+		    line[user_len] == ':') {
+			rc = PAM_SUCCESS;
+			break;
+		}
+		/* Has a newline been read?  */
+		line_len = strlen(line);
+		if (line_len < sizeof(line) - 1 ||
+		    line[line_len - 1] == '\n') {
+			/* Yes, continue with the next line.  */
+			continue;
+		}
+
+		/* No, read till the end of this line first.  */
+		while ((str = fgets(line, sizeof(line), fp)) != NULL) {
+			line_len = strlen(line);
+			if (line_len == 0 ||
+			    line[line_len - 1] == '\n') {
+				break;
+			}
+		}
+		if (str == NULL) {
+			/* fgets returned NULL, we are done.  */
+			break;
+		}
+		/* Continue with the next line.  */
+	}
+
+	fclose(fp);
+	return rc;
+}
+
+int
+pam_sm_authenticate(pam_handle_t *pamh, int flags UNUSED,
+		    int argc, const char **argv)
+{
+	int i;
+	int rc;
+	int debug = 0;
+	const char *file_name = NULL;
+	const char *user_name = NULL;
+
+	/* Process arguments.  */
+	for (i = 0; i < argc; ++i) {
+		if (strcmp("debug", argv[i]) == 0) {
+			debug = 1;
+		}
+	}
+	for (i = 0; i < argc; ++i) {
+		const char *str;
+
+		if (strcmp("debug", argv[i]) == 0) {
+			/* Already processed.  */
+			continue;
+		}
+		if ((str = pam_str_skip_prefix(argv[i], "file=")) != NULL) {
+			file_name = str;
+			if (debug) {
+				pam_syslog(pamh, LOG_DEBUG,
+					   "set filename to %s", file_name);
+			}
+		} else {
+			pam_syslog(pamh, LOG_ERR, "unrecognized option: %s",
+				   argv[i]);
+		}
+	}
+
+	/* Obtain the user name.  */
+	if ((rc = pam_get_user(pamh, &user_name, NULL)) != PAM_SUCCESS) {
+		pam_syslog(pamh, LOG_NOTICE, "cannot determine user name: %s",
+			   pam_strerror(pamh, rc));
+		return rc == PAM_CONV_AGAIN ? PAM_INCOMPLETE : rc;
+	}
+
+	return check_user_in_passwd(pamh, user_name, file_name);
+}
+
+int
+pam_sm_setcred(pam_handle_t *pamh UNUSED, int flags UNUSED,
+	       int argc UNUSED, const char **argv UNUSED)
+{
+	return PAM_SUCCESS;
+}
+
+int
+pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	return pam_sm_authenticate(pamh, flags, argc, argv);
+}
+
+int
+pam_sm_open_session(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	return pam_sm_authenticate(pamh, flags, argc, argv);
+}
+
+int
+pam_sm_close_session(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	return pam_sm_authenticate(pamh, flags, argc, argv);
+}
+
+int
+pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	return pam_sm_authenticate(pamh, flags, argc, argv);
+}