svn rev #24399: trunk/src/lib/gssapi/krb5/

[ghudson@MIT.EDU]

http://src.mit.edu/fisheye/changelog/krb5/?cs=24399
Commit By: ghudson
Log Message:
ticket: 6768
subject: GSSAPI forwarded credentials must be encrypted in session key
target_version: 1.8.4
tags: pullup

When IAKERB support was added, the krb5_mk_req checksum function
gained access to the send subkey.  This caused GSSAPI forwarded
credentials to be encrypted in the subkey, which violates RFC 4121
section 4.1.1 and is not accepted by Microsoft's implementation.
Temporarily null out the send subkey in the auth context so that
krb5_mk_ncred uses the session key instead.



Changed Files:
U   trunk/src/lib/gssapi/krb5/init_sec_context.c
Modified: trunk/src/lib/gssapi/krb5/init_sec_context.c
===================================================================
--- trunk/src/lib/gssapi/krb5/init_sec_context.c	2010-09-30 21:57:42 UTC (rev 24398)
+++ trunk/src/lib/gssapi/krb5/init_sec_context.c	2010-10-01 03:45:43 UTC (rev 24399)
@@ -270,9 +270,7 @@
     krb5_gss_ctx_ext_t exts;
 };
 
-#ifdef CFX_EXERCISE
 #include "../../krb5/krb/auth_con.h"
-#endif
 static krb5_error_code KRB5_CALLCONV
 make_gss_checksum (krb5_context context, krb5_auth_context auth_context,
                    void *cksum_data, krb5_data **out)
@@ -284,6 +282,7 @@
     krb5_data credmsg;
     unsigned int junk;
     krb5_data *finished = NULL;
+    krb5_key send_subkey;
 
     data->checksum_data.data = 0;
     credmsg.data = 0;
@@ -299,13 +298,22 @@
 
         assert(data->cred->name != NULL);
 
+        /*
+         * RFC 4121 4.1.1 specifies forwarded credentials must be encrypted in
+         * the session key, but krb5_fwd_tgt_creds will use the send subkey if
+         * it's set in the auth context.  Null out the send subkey temporarily.
+         */
+        send_subkey = auth_context->send_subkey;
+        auth_context->send_subkey = NULL;
+
         code = krb5_fwd_tgt_creds(context, auth_context, 0,
                                   data->cred->name->princ, data->ctx->there->princ,
                                   data->cred->ccache, 1,
                                   &credmsg);
 
-        /* turn KRB5_AUTH_CONTEXT_DO_TIME back on */
+        /* Turn KRB5_AUTH_CONTEXT_DO_TIME back on and reset the send subkey. */
         krb5_auth_con_setflags(context, auth_context, con_flags);
+        auth_context->send_subkey = send_subkey;
 
         if (code) {
             /* don't fail here; just don't accept/do the delegation