On 06/25/2013 02:55 PM, Lukas Slebodnik wrote:
On (24/06/13 17:04), Ondrej Kos wrote:
The problem here wasn't in returned error code, but in faultly read
DBUS message, due to condition in sss_authtok_set_string.
When password is empty, it passes 0 as length, which is
misinterpreted, and the function tries to determine the length of
string by itself, reaching over boundaries of authtok string.
trac issue: https://fedorahosted.org/sssd/ticket/1814
Patch is attached
Ondra
--
Ondrej Kos
Associate Software Engineer
Identity Management - SSSD
Red Hat Czech
From 7f7e34e3d64b2b7f3c02225ed506791106c8d8a9 Mon Sep 17 00:00:00 2001
From: Ondrej Kos <o...@redhat.com>
Date: Mon, 24 Jun 2013 16:58:23 +0200
Subject: [PATCH] Do not try to set password when authtok_length is zero
https://fedorahosted.org/sssd/ticket/1814
When the authtok_length is zero, it shouldn't call
sss_authtok_set_password, because it tries to determine lenght of passed
string by itself and would read parts of DBus message behind boundaries
of authtok.
---
src/responder/pam/pamsrv_cmd.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/src/responder/pam/pamsrv_cmd.c b/src/responder/pam/pamsrv_cmd.c
index
ff86a13a5ac13856a65d1618056caf4657cb473a..bf9a686230e0deb39f7387ed3f51c08f97575007
100644
--- a/src/responder/pam/pamsrv_cmd.c
+++ b/src/responder/pam/pamsrv_cmd.c
@@ -65,8 +65,12 @@ static int extract_authtok_v2(TALLOC_CTX *mem_ctx, struct
sss_auth_token *tok,
sss_authtok_set_empty(tok);
break;
case SSS_AUTHTOK_TYPE_PASSWORD:
- ret = sss_authtok_set_password(tok, (const char *)auth_token_data,
- auth_token_length);
+ if (auth_token_length == 0) {
+ sss_authtok_set_empty(tok);
+ } else {
+ ret = sss_authtok_set_password(tok, (const char *)auth_token_data,
+ auth_token_length);
+ }
break;
default:
return EINVAL;
--
1.8.1.4
I tried this patch and you did not reach krb5 authentication in krb5_child,
but reason is:
#>[krb5_auth_send] (0x0020): Wrong authtok type for user [usersssd01].
#> Expected [1], got [0]
So it failed in sssd_be
I tried next patch:
+ if (auth_token_length == 0) {
+ ret = sss_authtok_set_password(tok, "", 0);
+ } else {
+ ret = sss_authtok_set_password(tok, (const char *)auth_token_data,
+ auth_token_length);
+ }
and then it will fail in sssd_pam
#> [pam_parse_in_data_v3] (0x0020): pam_parse_in_data_v2 failed,
because sss_authtok_set_password could not be run with empty password.
So there is question:
where should we fail? (in sssd_be or sssd_pam)
The question is: do we want to allow empty password for non krb
authentication? If yes, than we should fail in sssd_be. If no, we can
fail in sssd_pam.
The current authtoken code suggest that we do not allow empty passwords
at all. See: sss_authtok_set_string().
Does LDAP support bind with empty password?
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