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From 9dcead87e6d7f66d34e7a56d11a30daca367dffb Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Wed, 26 Mar 2014 22:17:23 +0000
Subject: pam_timestamp: fix potential directory traversal issue (ticket #27)
pam_timestamp uses values of PAM_RUSER and PAM_TTY as components of
the timestamp pathname it creates, so extra care should be taken to
avoid potential directory traversal issues.
* modules/pam_timestamp/pam_timestamp.c (check_tty): Treat
"." and ".." tty values as invalid.
(get_ruser): Treat "." and ".." ruser values, as well as any ruser
value containing '/', as invalid.
Fixes CVE-2014-2583.
Reported-by: Sebastian Krahmer <krahmer@suse.de>
--- a/modules/pam_timestamp/pam_timestamp.c
+++ b/modules/pam_timestamp/pam_timestamp.c
@@ -158,7 +158,7 @@ check_tty(const char *tty)
tty = strrchr(tty, '/') + 1;
}
/* Make sure the tty wasn't actually a directory (no basename). */
- if (strlen(tty) == 0) {
+ if (!strlen(tty) || !strcmp(tty, ".") || !strcmp(tty, "..")) {
return NULL;
}
return tty;
@@ -243,6 +243,17 @@ get_ruser(pam_handle_t *pamh, char *ruserbuf, size_t ruserbuflen)
if (pwd != NULL) {
ruser = pwd->pw_name;
}
+ } else {
+ /*
+ * This ruser is used by format_timestamp_name as a component
+ * of constructed timestamp pathname, so ".", "..", and '/'
+ * are disallowed to avoid potential path traversal issues.
+ */
+ if (!strcmp(ruser, ".") ||
+ !strcmp(ruser, "..") ||
+ strchr(ruser, '/')) {
+ ruser = NULL;
+ }
}
if (ruser == NULL || strlen(ruser) >= ruserbuflen) {
*ruserbuf = '\0';
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