Bug #74636 [Asn]: [krb5] negotiate auth broken for vhosts because of hostname canonicalization

Edit report at https://bugs.php.net/bug.php?id=74636&edit=1 ID: 74636 User updated by: chanlists at googlemail dot com Reported by: chanlists at googlemail dot com Summary: [krb5] negotiate auth broken for vhosts because of hostname canonicalization Status: Assigned Type: Bug Package: PECL Operating System: debian 8 PHP Version: 5.6.30 Assigned To: mbechler Block user comment: N Private report: N New Comment: I can confirm that previously dns canonicalization had to be turned off. With your new code, if I specify the service principle as an argument to the constructor, it works regardless of the dns_canonicalize_hostname setting in /etc/krb5.conf. This seems to resolve the issues I raised. Thanks a lot for fixing it! Cheers, Christian Previous Comments: ------------------------------------------------------------------------ [2017-05-23 11:28:33] mbechler at eenterphace dot org Regarding the canonicalization, really looks like GSS_C_NT_HOSTBASED_SERVICE name types may be canonicalized. Can you verify that it is fixed by using GSS_KRB5_NT_PRINCIPAL_NAME and passing "HTTP/%s" instead. Downside might be that domain->realm is probably not applied (therefor always uses the default realm), so I would probably leave it as is for the "magic" case. Just commited a change adding the argument and parsing the name in that case with GSS_KRB5_NT_PRINCIPAL_NAME, that way the default would be the best guess we are able to make while allowing total control when overriding it. ------------------------------------------------------------------------ [2017-05-23 10:03:35] mbechler at eenterphace dot org Absolutely right, that is missing and I had noticed that before and even thought that I had added it - but that does not seem to be the case. Adding a constructor argument to KRB5NegotiateAuth for overriding the SPN sounds good? I think that would be the most obvious choice. Do you really need to disable "dns_canonicalize_hostname" (except for the client if it is run on the same host)? It would really surprise me if the library did perform hostname canonicalization on the server name for acceptor credentials. If you provide a patch, I'll be happy to merge that. ------------------------------------------------------------------------ [2017-05-23 09:38:38] chanlists at googlemail dot com I would actually prefer to be able to set the service principle using a method that changes a property, and use the current behavior as the default method.... ------------------------------------------------------------------------ [2017-05-23 09:29:22] requinix@php.net This sounds like something that should be controlled by an INI setting. ------------------------------------------------------------------------ [2017-05-23 09:09:04] chanlists at googlemail dot com Description: ------------ Suppose we are using a virtual host in apache where the name of the virtual host name <vhost> is a cname for the actual hostname <hostname>. In this case, the web browser will present a service ticket for HTTP/<vhost>, but the krb5 package will set the service principal to HTTP/<hostname> because of the use of gethostbyname() in the KRB5NegotiateAuth constructor. This will not work. If I modify the constructor as follows, it works: server_name = zend_compat_hash_find(HASH_OF(server), "SERVER_NAME", sizeof("SERVER_NAME")); if ( server_name != NULL ) { char *hostname = Z_STRVAL_P(server_name); // struct hostent* host = gethostbyname(hostname); // if(!host) { // zend_throw_exception(NULL, "Failed to get server FQDN - Lookup failure", 0 TSRMLS_CC); // return; //} nametmp.length = strlen(hostname) + 6; nametmp.value = emalloc(sizeof(char)*nametmp.length); snprintf(nametmp.value, nametmp.length, "HTTP@%s",hostname); Note that for this to work, one also has to set dns_canonicalize_hostname = false in /etc/krb5.conf because otherwise the krb5 library will try to do hostname canonicalization as well. So I think there should either be a way to set the name of the service principal using a method, or hostname canonicalization should be disabled in the krb5 library as above, or it should be possible to turn it off with a flag. I would be happy to contribute a patch depending on what you prefer. Thanks for this great piece of software, Christian Test script: --------------- see above ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74636&edit=1