r13481: As far as I can tell, my changes in -r 12863 were dangerously untested.

We do need the gsskrb5_get_initiator_subkey() routine.  But we should
ensure that we do always get a valid key, to prevent any segfaults.

Without this code, we get a different session key compared with
Win2k3, and so kerberised smb signing fails.

Andrew Bartlett
(This used to be commit cfd0df16b7)

source4/auth/gensec/gensec_gssapi.c

@@ -1058,21 +1058,22 @@ static NTSTATUS gensec_gssapi_session_key(struct gensec_security *gensec_securit
 	if ((gensec_gssapi_state->gss_oid->length == gss_mech_krb5->length)
 	    && (memcmp(gensec_gssapi_state->gss_oid->elements, gss_mech_krb5->elements, 
 		       gensec_gssapi_state->gss_oid->length) == 0)) {
-		OM_uint32 maj_stat;
-		krb5_keyblock *skey;
+		OM_uint32 maj_stat, min_stat;
+		gss_buffer_desc skey;
 		
-		maj_stat = gss_krb5_get_subkey(gensec_gssapi_state->gssapi_context, 
-					       &skey);
+		maj_stat = gsskrb5_get_initiator_subkey(&min_stat, 
+							gensec_gssapi_state->gssapi_context, 
+							&skey);
 		
 		if (maj_stat == 0) {
 			DEBUG(10, ("Got KRB5 session key of length %d\n",  
-				   (int)KRB5_KEY_LENGTH(skey)));
+				   (int)skey.length));
 			gensec_gssapi_state->session_key = data_blob_talloc(gensec_gssapi_state, 
-									    KRB5_KEY_DATA(skey), KRB5_KEY_LENGTH(skey));
+									    skey.value, skey.length);
 			*session_key = gensec_gssapi_state->session_key;
 			dump_data_pw("KRB5 Session Key:\n", session_key->data, session_key->length);
 			
-			krb5_free_keyblock(gensec_gssapi_state->smb_krb5_context->krb5_context, skey);
+			gss_release_buffer(&min_stat, &skey);
 			return NT_STATUS_OK;
 		}
 		return NT_STATUS_NO_USER_SESSION_KEY;

source4/auth/kerberos/kerberos-notes.txt

@@ -247,6 +247,10 @@ the kerberos libraries
 
  - DCE_STYLE
 
+ - gsskrb5_get_initiator_subkey() (return the exact key that Samba3
+   has always asked for.  gsskrb5_get_subkey() might do what we need
+   anyway)
+
  - gsskrb5_acquire_creds() (takes keytab and/or ccache as input
    parameters, see keytab and state machine discussion)
 

source4/heimdal/lib/gssapi/gssapi.h

@@ -815,8 +815,10 @@ gsskrb5_extract_authtime_from_sec_context(OM_uint32 *minor_status,
 					  gss_ctx_id_t context_handle,
 					  time_t *authtime);
 OM_uint32
-gss_krb5_get_subkey(const gss_ctx_id_t context_handle,
-		    struct EncryptionKey **key);
+gsskrb5_get_initiator_subkey
+        (OM_uint32 * /*minor_status*/,
+	 const gss_ctx_id_t context_handle,
+	 gss_buffer_t /* subkey */);
 
 #define GSS_C_KRB5_COMPAT_DES3_MIC 1
 

source4/heimdal/lib/gssapi/gssapi_locl.h

@@ -226,6 +226,9 @@ gss_verify_mic_internal(OM_uint32 * minor_status,
 			gss_qop_t * qop_state,
 			char * type);
 
+OM_uint32
+gss_krb5_get_subkey(const gss_ctx_id_t context_handle,
+		    krb5_keyblock **key);
 
 krb5_error_code
 gss_address_to_krb5addr(OM_uint32 gss_addr_type,

source4/heimdal/lib/gssapi/wrap.c

@@ -35,6 +35,61 @@
 
 RCSID("$Id: wrap.c,v 1.31 2005/01/05 02:52:12 lukeh Exp $");
 
+OM_uint32
+gsskrb5_get_initiator_subkey(OM_uint32 *minor_status,
+			     gss_ctx_id_t context_handle,
+			     gss_buffer_t key)
+{
+    krb5_error_code ret;
+    krb5_keyblock *skey = NULL;
+
+    HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
+    if (context_handle->more_flags & LOCAL) {
+	ret = krb5_auth_con_getlocalsubkey(gssapi_krb5_context,
+					   context_handle->auth_context, 
+					   &skey);
+	if (ret) {
+		*minor_status = ret;
+		return GSS_KRB5_S_KG_NO_SUBKEY; /* XXX */
+	}
+	
+    } else {
+	ret = krb5_auth_con_getremotesubkey(gssapi_krb5_context,
+					    context_handle->auth_context, 
+					    &skey);
+	if (ret) {
+		*minor_status = ret;
+		return GSS_KRB5_S_KG_NO_SUBKEY; /* XXX */
+	}
+    
+    }
+    
+    /* If there was no subkey, perhaps try this... */
+    if(skey == NULL) {
+	krb5_auth_con_getkey(gssapi_krb5_context,
+			     context_handle->auth_context, 
+			     &skey);
+    }
+
+    HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
+
+    /* ensure never to segfault */
+    if(skey == NULL) {
+	return GSS_KRB5_S_KG_NO_SUBKEY; /* XXX */
+    }
+
+    key->length = skey->keyvalue.length;
+    key->value  = malloc (key->length);
+    if (!key->value) {
+	    krb5_free_keyblock(gssapi_krb5_context, skey);
+	    *minor_status = ENOMEM;
+	    return GSS_S_FAILURE;
+    }
+    memcpy(key->value, skey->keyvalue.data, key->length);
+    krb5_free_keyblock(gssapi_krb5_context, skey);
+    return 0;
+}
+
 OM_uint32
 gss_krb5_get_subkey(const gss_ctx_id_t context_handle,
 		    krb5_keyblock **key)