On 04/08/2013 03:55 PM, Martin Kosek wrote:
On 04/01/2013 09:52 PM, Rob Crittenden wrote:
Tomas Babej wrote:
On 02/12/2013 06:23 PM, Simo Sorce wrote:
On Tue, 2013-02-12 at 18:03 +0100, Tomas Babej wrote:
On 02/12/2013 05:50 PM, Tomas Babej wrote:
Hi,

This patch adds a check for krbprincipalexpiration attribute to
pre_bind operation
in ipa-pwd-extop dirsrv plugin. If the principal is expired, auth is
denied and LDAP_INVALID_CREDENTIALS along with the error message is
sent back to the client. Since krbprincipalexpiration attribute is
not
mandatory, if there is no value set, the check is passed.

https://fedorahosted.org/freeipa/ticket/3305
Comments inline.
@@ -1166,6 +1173,29 @@ static int ipapwd_pre_bind(Slapi_PBlock *pb)
           goto done;
       }
+    /* check the krbPrincipalExpiration attribute is present */
+    ret = slapi_entry_attr_find(entry, "krbPrincipalExpiration",
&attr);
+    if (!ret) {
ret is not a boolean so probably better ti use (ret != 0)

+        /* if it is, check whether the principal has not expired */
+
+        principal_expire = slapi_entry_attr_get_charptr(entry,
+                               "krbprincipalexpiration");
+        memset(&expire_tm, 0, sizeof (expire_tm));
+
+        if (strptime(principal_expire, "%Y%m%d%H%M%SZ", &expire_tm)){
style issue missing space between ) and {

+            expire_time = mktime(&expire_tm);
+            /* this might have overflown on 32-bit system */
This comment does not help to point out what you want to put in
evidence.
if there is an overflow what is the consequence ? Or does it mean the
next condition is taking that into account ?
Yeah, this was rather ill-worded. Replaced by a rather verbose
comment that hopefully clears things out.
+            if (current_time > expire_time && expire_time > 0){
style issue missing space between ) and {

+                LOG_FATAL("kerberos principal has expired in user
entry: %s\n",
+                          dn);
I think a better phrasing would be: "The kerberos principal on %s is
expired\n"

+                errMesg = "Kerberos principal has expired.";
s/has/is/

The rest looks good to me.

Simo.
Styling issues fixed and updated patch attached :)
Small nit, the expiration error should probably use 'in' not 'on'.

I'm not sure LDAP_INVALID_CREDENTIALS is the right return code. This implies
that the password is wrong. I think that LDAP_UNWILLING_TO_PERFORM is probably
more correct here. It is what we return on other policy failures.

rob

Additional findings:

1) Lets not try to get current_time every time, but only when its needed (i.e.
krbPrincipalExpiration is set) - AFAIK, it is not so cheap operation:

+    /* get current time*/
+    current_time = time(NULL);

2) Why using slapi_entry_attr_get_charptr and thus let 389-ds find the
attribute again when we already have a pointer for the attribute? Would
slapi_attr_first_value following slapi_entry_attr_find be faster approach?

+    ret = slapi_entry_attr_find(entry, "krbPrincipalExpiration", &attr);
+    if (ret != 0) {
+        /* if it is, check whether the principal has not expired */
+
+        principal_expire = slapi_entry_attr_get_charptr(entry,
+                               "krbprincipalexpiration");

This way, we would not create a copy of this attribute value - we do not need a
copy, we just do check against it.


3) Shouldn't we return -1 in the end when the auth fails? We do that in other
pre_callbacks. Otherwise we just return 0 (success):

+    if (auth_failed){
+        slapi_send_ldap_result(pb, LDAP_INVALID_CREDENTIALS, NULL, errMesg,
+                               0, NULL);
+    }
+
      return 0;

Martin

Thank you both for the review. I updated and retested the patch, with your suggestions incorporated.

Tomas
>From ee196a301e4d17ee8cedfc14e87fc44a2bc7b6b9 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tba...@redhat.com>
Date: Mon, 11 Feb 2013 15:33:12 +0100
Subject: [PATCH] Deny LDAP binds for user accounts with expired principal

Adds a check for krbprincipalexpiration attribute to pre_bind operation
in ipa-pwd-extop dirsrv plugin. If the principal is expired, auth is
denied and LDAP_INVALID_CREDENTIALS along with the error message is
sent back to the client. Since krbprincipalexpiration attribute is not
mandatory, if there is no value set, the check is passed.

https://fedorahosted.org/freeipa/ticket/3305
---
 .../ipa-pwd-extop/ipapwd_prepost.c                 | 45 +++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/daemons/ipa-slapi-plugins/ipa-pwd-extop/ipapwd_prepost.c b/daemons/ipa-slapi-plugins/ipa-pwd-extop/ipapwd_prepost.c
index 0318cecdcc37690838ffc778817cd60c9a8376a0..444f2824334db313afab2330de2ab2cdecbdc84b 100644
--- a/daemons/ipa-slapi-plugins/ipa-pwd-extop/ipapwd_prepost.c
+++ b/daemons/ipa-slapi-plugins/ipa-pwd-extop/ipapwd_prepost.c
@@ -1127,13 +1127,17 @@ static int ipapwd_pre_bind(Slapi_PBlock *pb)
     Slapi_Value *value = NULL;
     Slapi_Attr *attr = NULL;
     struct tm expire_tm;
+    time_t current_time;
+    time_t expire_time;
     char *errMesg = "Internal operations error\n"; /* error message */
     char *expire = NULL; /* passwordExpirationTime attribute value */
+    char *principal_expire = NULL; /* krbPrincipalExpiration attribute value */
     char *dn = NULL; /* bind DN */
     Slapi_Value *objectclass;
     int method; /* authentication method */
     int ret = 0;
     char *principal = NULL;
+    bool auth_failed = false;
 
     LOG_TRACE("=>\n");
 
@@ -1154,7 +1158,7 @@ static int ipapwd_pre_bind(Slapi_PBlock *pb)
     const char *attrs_list[] = {SLAPI_USERPWD_ATTR, "krbprincipalkey", "uid",
                                 "krbprincipalname", "objectclass",
                                 "passwordexpirationtime",  "passwordhistory",
-                                NULL};
+                                "krbprincipalexpiration", NULL};
 
     /* retrieve user entry */
     ret = ipapwd_getEntry(dn, &entry, (char **) attrs_list);
@@ -1170,6 +1174,39 @@ static int ipapwd_pre_bind(Slapi_PBlock *pb)
         goto done;
     }
 
+    /* check the krbPrincipalExpiration attribute is present */
+    ret = slapi_entry_attr_find(entry, "krbPrincipalExpiration", &attr);
+    if (ret == 0) {
+        ret = slapi_attr_first_value(attr, &value);
+
+        if (ret == 0) {
+            /* if it is, check whether the principal has not expired */
+            principal_expire = slapi_value_get_string(value);
+            memset(&expire_tm, 0, sizeof (expire_tm));
+
+            if (strptime(principal_expire, "%Y%m%d%H%M%SZ", &expire_tm)) {
+                expire_time = mktime(&expire_tm);
+
+                /* get current time */
+                current_time = time(NULL);
+
+                /* mktime returns -1 if the tm struct cannot be represented as
+                 * as calendar time (seconds since the Epoch). This might
+                 * happen with tm structs that are ill-formated or on 32-bit
+                 * platforms with dates that would cause overflow
+                 * (year 2038 and later).
+                 * In such cases, skip the expiration check. */
+
+                if (current_time > expire_time && expire_time > 0) {
+                    LOG_FATAL("kerberos principal in %s is expired\n", dn);
+                    errMesg = "Kerberos principal is expired.";
+                    auth_failed = true;
+                    goto done;
+                    }
+                }
+        }
+    }
+
     /* we aren't interested in host principals */
     objectclass = slapi_value_new_string("ipaHost");
     if ((slapi_entry_attr_has_syntax_value(entry, SLAPI_ATTR_OBJECTCLASS, objectclass)) == 1) {
@@ -1292,6 +1329,12 @@ done:
         slapi_entry_free(entry);
     free_ipapwd_krbcfg(&krbcfg);
 
+    if (auth_failed){
+        slapi_send_ldap_result(pb, LDAP_UNWILLING_TO_PERFORM, NULL, errMesg,
+                               0, NULL);
+        return -1;
+    }
+
     return 0;
 }
 
-- 
1.8.1.4

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