fix CVE-2013-7041: use case sensitive comparison in pam_userdb

pam-1.1.8-cve-2013-7041.patch

@@ -0,0 +1,52 @@
+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: [PATCH] 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
+---
+ modules/pam_userdb/pam_userdb.c | 9 ++++++---
+ 1 file changed, 6 insertions(+), 3 deletions(-)
+
+diff --git a/modules/pam_userdb/pam_userdb.c b/modules/pam_userdb/pam_userdb.c
+index de8b5b1..ff040e6 100644
+--- 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");
+ 	      }
+ 	    };
+ 
+-- 
+1.8.3.1
+