| 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 |
| Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar> |
| |
| 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"); |
| } |
| }; |
| |
| -- |
| cgit v0.10.2 |
| |
