[SSSD] [PATCH] LDAP: Make it possible to use full principal in ldap_sasl_authid again

Stephen Gallagher sgallagh at redhat.com
Mon Nov 19 15:54:43 UTC 2012


On Mon 19 Nov 2012 10:35:43 AM EST, Jakub Hrozek wrote:
> On Mon, Nov 19, 2012 at 02:29:59PM +0100, Pavel Březina wrote:
>> On 11/19/2012 11:53 AM, Jakub Hrozek wrote:
>>> The behaviour of ldap_sasl_authid was changed in
>>> e81a816cddab4a62f263d1a0274d5d3f101e8e0f so that it no longer accepted full
>>> principal, but only hostname. The realm was read from the (undocumented)
>>> ldap_sasl_realm option.
>>>
>>> Moreover the "hostname" had to be specified in exactly the format that would
>>> match the keytab later, ie if the first match was host/hostname, the option
>>> would have to be specified as host/hostname, otherwise the user got an error.
>>>
>>> I also found out that the principal selection is only used in IPA and AD
>>> providers, but I'll file a separate ticket to track that. Right now, I'm
>>> mostly interested in fixing the regression.
>>>
>>> The attached patched modify that behaviour:
>>>
>>> [PATCH 1/3] MAN: document the ldap_sasl_realm option
>>> The option was completely undocumented.
>>>
>>> [PATCH 2/3] LDAP: Provide a common sdap_set_sasl_options init function
>>> The AD and IPA initialization functions shared the same code. This patch
>>> moves the code into a common initialization function.
>>> [PATCH 3/3] LDAP: Make it possible to use full principal in ldap_sasl_authid again
>>> When the guessing of principals was introduced, we changed the existing
>>> behaviour and instead of allowing both host/hostname at REALM and
>>> host/hostname, only the latter worked and the realm was always appended
>> >from the (then undocumented) ldap_sasl_realm option.
>>>
>>> This patch changes the behaviour to be more backwards-compatible -- if
>>> the ldap_sasl_authid contains the @-sign, then the ldap_sasl_realm is
>>> not always appended.
>>>
>>> The strict requirement of checking the requested authid/realm against
>>> the one found in keytab was also kind of relaxed because it didn't
>>> really work. For example when hostname was requested and the keytab
>>> matched host/hostname first, the code blew up.
>>>
>>> https://fedorahosted.org/sssd/ticket/1635
>>
>> Hi,
>>
>>> -    if ((primary_requested && strcmp(desired_primary, sasl_primary) != 0) ||
>>> -        (realm_requested && strcmp(desired_realm, sasl_realm) != 0)) {
>>> -        DEBUG(SSSDBG_CRIT_FAILURE,
>>> -               ("Configured SASL auth ID/realm not found in keytab.\n"));
>>> -        ret = ENOENT;
>>> -        goto done;
>>> +    if (primary_requested && strcmp(desired_primary, sasl_primary) != 0) {
>>> +        DEBUG(SSSDBG_MINOR_FAILURE,
>>> +               ("Configured SASL auth ID not found in keytab. "
>>> +                "Requested %s, found %s\n", desired_primary, sasl_primary));
>>> +    }
>>> +
>>> +    if (realm_requested && strcmp(desired_realm, sasl_realm) != 0) {
>>> +        DEBUG(SSSDBG_MINOR_FAILURE,
>>> +               ("Configured SASL realm not found in keytab. "
>>> +                "Requested %s, found %s\n", desired_realm, sasl_realm));
>>>      }
>>
>> Nack.
>>
>> I agree with splitting the condition but can you do it in patch #2?
>
> Done.
>

Sorry, I wish I had seen this request earlier. Please separate this 
into its own patch. Patches that move functions from one location to a 
common location should do that and nothing else. Moving and changing at 
the same time makes it difficult to review or examine later.

>>
>> Also you are not interpreting it as error any longer. Is it intentional?
>
> The check is too restrictive as the select_principal_from_keytab can
> return something else than you requested right now.
>
> Consider that you query for host/myserver at EXAMPLE.COM, then the
> select_principal_from_keytab function will return "myserver" in primary
> and "EXAMPLE.COM" in realm. So you'd need to add logic to also break
> down the principal to get rid of the host/ part. I think the heuristics
> would simply get too complex.
>
> select_principal_from_keytab will error out anyway if there's no
> suitable principal at all.


Yes, this is the correct behavior, though as I said above, please move 
functional changes into a separate patch from the de-duplication patch.



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