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From 9dcead87e6d7f66d34e7a56d11a30daca367dffb Mon Sep 17 00:00:00 2001
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From: "Dmitry V. Levin" <ldv@altlinux.org>
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Date: Wed, 26 Mar 2014 22:17:23 +0000
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Subject: [PATCH] pam_timestamp: fix potential directory traversal issue
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(ticket #27)
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pam_timestamp uses values of PAM_RUSER and PAM_TTY as components of
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the timestamp pathname it creates, so extra care should be taken to
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avoid potential directory traversal issues.
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* modules/pam_timestamp/pam_timestamp.c (check_tty): Treat
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"." and ".." tty values as invalid.
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(get_ruser): Treat "." and ".." ruser values, as well as any ruser
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value containing '/', as invalid.
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Fixes CVE-2014-2583.
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Reported-by: Sebastian Krahmer <krahmer@suse.de>
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---
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modules/pam_timestamp/pam_timestamp.c | 13 ++++++++++++-
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1 file changed, 12 insertions(+), 1 deletion(-)
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diff --git a/modules/pam_timestamp/pam_timestamp.c b/modules/pam_timestamp/pam_timestamp.c
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index 5193733..b3f08b1 100644
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--- a/modules/pam_timestamp/pam_timestamp.c
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+++ b/modules/pam_timestamp/pam_timestamp.c
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@@ -158,7 +158,7 @@ check_tty(const char *tty)
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tty = strrchr(tty, '/') + 1;
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}
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/* Make sure the tty wasn't actually a directory (no basename). */
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- if (strlen(tty) == 0) {
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+ if (!strlen(tty) || !strcmp(tty, ".") || !strcmp(tty, "..")) {
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return NULL;
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}
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return tty;
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@@ -243,6 +243,17 @@ get_ruser(pam_handle_t *pamh, char *ruserbuf, size_t ruserbuflen)
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if (pwd != NULL) {
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ruser = pwd->pw_name;
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}
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+ } else {
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+ /*
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+ * This ruser is used by format_timestamp_name as a component
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+ * of constructed timestamp pathname, so ".", "..", and '/'
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+ * are disallowed to avoid potential path traversal issues.
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+ */
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+ if (!strcmp(ruser, ".") ||
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+ !strcmp(ruser, "..") ||
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+ strchr(ruser, '/')) {
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+ ruser = NULL;
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+ }
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}
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if (ruser == NULL || strlen(ruser) >= ruserbuflen) {
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*ruserbuf = '\0';
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--
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1.8.3.1
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