Re: Bug#757555: pam: CVE-2014-2583 pam_timestamp directory traversal issues
control: tag -1 patch
On Sat, Aug 9, 2014 at 9:46 PM, Steve Langasek wrote:
> Which according to elsewhere in my mailbox, you've dealt with by uploading a
> 10-day delayed NMU. This is unacceptable
Sorry for not getting the nmu mail out in a timely manner, but real
life got in the way.
What is not acceptable is the assumed bad faith and the misguided
attempt at public shaming (after only half a day) without considering
the possibility of RL events or other benign possibilities. A simple
"hey, what's going on with this thing I'm seeing in deferred" mail
directed at me would have been the kind thing to do.
> I have removed pam_1.1.3-8.1_amd64.changes from the delayed queue. If you
> have changes that you would like to see included in this package, please
> send them to the BTS where they belong.
The proposed patch is now attached. I plan to upload that to
delayed/5 after about a week or so to give you lots of additional time
for review (way more than the normal nmu process requires).
Best wishes,
Mike
diff -u pam-1.1.8/debian/changelog pam-1.1.8/debian/changelog
--- pam-1.1.8/debian/changelog
+++ pam-1.1.8/debian/changelog
@@ -1,3 +1,13 @@
+pam (1.1.8-3.1) unstable; urgency=high
+
+ * Non-maintainer upload by the Security Team.
+ * Fix CVE-2013-7041: case-insensitive comparison used for verifying
+ passwords in the pam_userdb module (closes: #731368).
+ * Fix CVE-2014-2583: multiple directory traversal issues in the
+ pam_timestamp module (closes: 757555)
+
+ -- Michael Gilbert <mgilbert@debian.org> Sat, 09 Aug 2014 09:50:42 +0000
+
pam (1.1.8-3) unstable; urgency=low
* debian/rules: On hurd, link libpam explicitly with -lpthread since glibc
diff -u pam-1.1.8/debian/patches-applied/series pam-1.1.8/debian/patches-applied/series
--- pam-1.1.8/debian/patches-applied/series
+++ pam-1.1.8/debian/patches-applied/series
@@ -23,0 +24,2 @@
+cve-2013-7041.patch
+cve-2014-2583.patch
only in patch2:
unchanged:
--- pam-1.1.8.orig/debian/patches-applied/cve-2013-7041.patch
+++ pam-1.1.8/debian/patches-applied/cve-2013-7041.patch
@@ -0,0 +1,44 @@
+From 57a1e2b274d0a6376d92ada9926e5c5741e7da20 Mon Sep 17 00:00:00 2001
+From: "Dmitry V. Levin" <ldv@altlinux.org>
+Date: Fri, 24 Jan 2014 22:18:32 +0000
+Subject: pam_userdb: fix password hash comparison
+
+Starting with commit Linux-PAM-0-77-28-g0b3e583 that introduced hashed
+passwords support in pam_userdb, hashes are compared case-insensitively.
+This bug leads to accepting hashes for completely different passwords in
+addition to those that should be accepted.
+
+Additionally, commit Linux-PAM-1_1_6-13-ge2a8187 that added support for
+modern password hashes with different lengths and settings, did not
+update the hash comparison accordingly, which leads to accepting
+computed hashes longer than stored hashes when the latter is a prefix
+of the former.
+
+* modules/pam_userdb/pam_userdb.c (user_lookup): Reject the computed
+hash whose length differs from the stored hash length.
+Compare computed and stored hashes case-sensitively.
+Fixes CVE-2013-7041.
+
+Bug-Debian: http://bugs.debian.org/731368
+
+--- a/modules/pam_userdb/pam_userdb.c
++++ b/modules/pam_userdb/pam_userdb.c
+@@ -222,12 +222,15 @@ user_lookup (pam_handle_t *pamh, const char *database, const char *cryptmode,
+ } else {
+ cryptpw = crypt (pass, data.dptr);
+
+- if (cryptpw) {
+- compare = strncasecmp (data.dptr, cryptpw, data.dsize);
++ if (cryptpw && strlen(cryptpw) == (size_t)data.dsize) {
++ compare = memcmp(data.dptr, cryptpw, data.dsize);
+ } else {
+ compare = -2;
+ if (ctrl & PAM_DEBUG_ARG) {
+- pam_syslog(pamh, LOG_INFO, "crypt() returned NULL");
++ if (cryptpw)
++ pam_syslog(pamh, LOG_INFO, "lengths of computed and stored hashes differ");
++ else
++ pam_syslog(pamh, LOG_INFO, "crypt() returned NULL");
+ }
+ };
+
only in patch2:
unchanged:
--- pam-1.1.8.orig/debian/patches-applied/cve-2014-2583.patch
+++ pam-1.1.8/debian/patches-applied/cve-2014-2583.patch
@@ -0,0 +1,47 @@
+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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