Re: [PATCH] Check for AD style machine principal name

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, May 05, 2010 at 07:53:33PM +0300, Timo Aaltonen wrote:
>
> CC:ing the "new" list.
>
> On Tue, 27 Apr 2010, J. Bruce Fields wrote:
>
>> On Mon, Apr 26, 2010 at 05:00:59PM +0300, timo.aaltonen-uOixanVlb7U@public.gmane.org wrote:
>>> @@ -737,6 +737,26 @@ gssd_search_krb5_keytab(krb5_context context, krb5_keytab kt,
>>>  }
>>>
>>>  /*
>>> + * Convert the hostname to machine principal name as created
>>> + * by MS Active Directory.
>>> +*/
>>> +
>>> +static char *
>>> +hostname_to_adprinc(char *name)
>>> +{
>>> +	int i = 0;
>>> +	char *buf = strdup(name);
>>
>> We should handle the possible NULL return.
>
> How about not calling hostname_to_adprinc from find_keytab_entry unless  
> myhostname is != NULL?

I'm not sure what you mean.  I'm just pointing out that strdup() can
return NULL if the memory allocation fails.

>
>>> +	int len = strlen(name);
>>> +	while(i < len) {
>>> +		buf[i] = toupper(buf[i]);
>>> +		i++;
>>> +	}
>>> +	buf[i++] = '$';
>>> +	buf[i] = 0;
>>
>> This is past the end of the buffer.  Maybe you want buf to be
>> strlen(name)+1?
>
> Ok, so:
>         char *buf = malloc(sizeof(name)+1);
> 	buf = strdup(name);
> 	.
> 	.
> works, and should be ok?

The strdup should be a strcpy.

>
>>> @@ -812,6 +836,35 @@ find_keytab_entry(krb5_context context, krb5_keytab kt, const char *hostname,
>>>  			break;
>>>  		if (strcmp(realm, default_realm) == 0)
>>>  			tried_default = 1;
>>> +		/* First try the Active Directory style machine principal */
>>> +		code = krb5_build_principal_ext(context, &princ,
>>> +						strlen(realm),
>>> +						realm,
>>> +						strlen(adprinc),
>>> +						adprinc,
>>> +						NULL);
>>> +		if (code) {
>>> +			k5err = gssd_k5_err_msg(context, code);
>>> +			printerr(1, "%s while building principal for "
>>> +				 "'%s@%s'\n", k5err,
>>> +				 adprinc, realm);
>>> +			continue;
>>
>> Is there an infinite loop here?
>
> Not to my knowledge,

We need a more convincing argument than that, unless someone else has
the cycles to take this over!

--b.

> it's basically the same chunk of code copied from a 
> few lines below, modified to suit the adprinc.
>
>
> -- 
> Timo Aaltonen
> Systems Specialist
> IT Services, Aalto University