Adding upstream version 2:4.20.0+dfsg.upstream/2%4.20.0+dfsg

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1438 insertions, 0 deletions

diff --git a/source3/librpc/crypto/gse.c b/source3/librpc/crypto/gse.c
new file mode 100644
index 0000000..ddda18e
--- /dev/null
+++ b/source3/librpc/crypto/gse.c
@@ -0,0 +1,1438 @@
+/*
+ *  GSSAPI Security Extensions
+ *  RPC Pipe client and server routines
+ *  Copyright (C) Simo Sorce 2010.
+ *  Copyright (C) Andrew Bartlett 2004-2011.
+ *  Copyright (C) Stefan Metzmacher <metze@samba.org> 2004-2005
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* We support only GSSAPI/KRB5 here */
+
+#include "includes.h"
+#include <tevent.h>
+#include "lib/util/tevent_ntstatus.h"
+#include "gse.h"
+#include "libads/kerberos_proto.h"
+#include "auth/common_auth.h"
+#include "auth/gensec/gensec.h"
+#include "auth/gensec/gensec_internal.h"
+#include "auth/credentials/credentials.h"
+#include "../librpc/gen_ndr/dcerpc.h"
+#include "param/param.h"
+
+#if defined(HAVE_KRB5)
+
+#include "auth/kerberos/pac_utils.h"
+#include "auth/kerberos/gssapi_helper.h"
+#include "gse_krb5.h"
+
+static char *gse_errstr(TALLOC_CTX *mem_ctx, OM_uint32 maj, OM_uint32 min);
+static size_t gensec_gse_sig_size(struct gensec_security *gensec_security,
+				  size_t data_size);
+
+struct gse_context {
+	gss_ctx_id_t gssapi_context;
+	gss_name_t server_name;
+	gss_name_t client_name;
+	OM_uint32 gss_want_flags, gss_got_flags;
+	size_t max_wrap_buf_size;
+	size_t sig_size;
+
+	gss_cred_id_t delegated_cred_handle;
+
+	NTTIME expire_time;
+
+	/* gensec_gse only */
+	krb5_context k5ctx;
+	krb5_ccache ccache;
+	krb5_keytab keytab;
+
+	gss_OID_desc gss_mech;
+	gss_cred_id_t creds;
+
+	gss_OID ret_mech;
+};
+
+/* free non talloc dependent contexts */
+static int gse_context_destructor(void *ptr)
+{
+	struct gse_context *gse_ctx;
+	OM_uint32 gss_min;
+
+	gse_ctx = talloc_get_type_abort(ptr, struct gse_context);
+	if (gse_ctx->k5ctx) {
+		if (gse_ctx->ccache) {
+			krb5_cc_close(gse_ctx->k5ctx, gse_ctx->ccache);
+			gse_ctx->ccache = NULL;
+		}
+		if (gse_ctx->keytab) {
+			krb5_kt_close(gse_ctx->k5ctx, gse_ctx->keytab);
+			gse_ctx->keytab = NULL;
+		}
+		krb5_free_context(gse_ctx->k5ctx);
+		gse_ctx->k5ctx = NULL;
+	}
+	if (gse_ctx->gssapi_context != GSS_C_NO_CONTEXT) {
+		(void)gss_delete_sec_context(&gss_min,
+						 &gse_ctx->gssapi_context,
+						 GSS_C_NO_BUFFER);
+	}
+	if (gse_ctx->server_name) {
+		(void)gss_release_name(&gss_min,
+					   &gse_ctx->server_name);
+	}
+	if (gse_ctx->client_name) {
+		(void)gss_release_name(&gss_min,
+					   &gse_ctx->client_name);
+	}
+	if (gse_ctx->creds) {
+		(void)gss_release_cred(&gss_min,
+					   &gse_ctx->creds);
+	}
+	if (gse_ctx->delegated_cred_handle) {
+		(void)gss_release_cred(&gss_min,
+					   &gse_ctx->delegated_cred_handle);
+	}
+
+	/* MIT and Heimdal differ as to if you can call
+	 * gss_release_oid() on this OID, generated by
+	 * gss_{accept,init}_sec_context().  However, as long as the
+	 * oid is gss_mech_krb5 (which it always is at the moment),
+	 * then this is a moot point, as both declare this particular
+	 * OID static, and so no memory is lost.  This assert is in
+	 * place to ensure that the programmer who wishes to extend
+	 * this code to EAP or other GSS mechanisms determines an
+	 * implementation-dependent way of releasing any dynamically
+	 * allocated OID */
+	SMB_ASSERT(smb_gss_oid_equal(&gse_ctx->gss_mech, GSS_C_NO_OID) ||
+		   smb_gss_oid_equal(&gse_ctx->gss_mech, gss_mech_krb5));
+
+	return 0;
+}
+
+static NTSTATUS gse_setup_server_principal(TALLOC_CTX *mem_ctx,
+					   const char *target_principal,
+					   const char *service,
+					   const char *hostname,
+					   const char *realm,
+					   char **pserver_principal,
+					   gss_name_t *pserver_name)
+{
+	char *server_principal = NULL;
+	gss_buffer_desc name_token;
+	gss_OID name_type;
+	OM_uint32 maj_stat, min_stat = 0;
+
+	if (target_principal != NULL) {
+		server_principal = talloc_strdup(mem_ctx, target_principal);
+		name_type = GSS_C_NULL_OID;
+	} else {
+		server_principal = talloc_asprintf(mem_ctx,
+						   "%s/%s@%s",
+						   service,
+						   hostname,
+						   realm);
+		name_type = GSS_C_NT_USER_NAME;
+	}
+	if (server_principal == NULL) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	name_token.value = (uint8_t *)server_principal;
+	name_token.length = strlen(server_principal);
+
+	maj_stat = gss_import_name(&min_stat,
+				   &name_token,
+				   name_type,
+				   pserver_name);
+	if (maj_stat) {
+		DBG_WARNING("GSS Import name of %s failed: %s\n",
+			    server_principal,
+			    gse_errstr(mem_ctx, maj_stat, min_stat));
+		TALLOC_FREE(server_principal);
+		return NT_STATUS_INVALID_PARAMETER;
+	}
+
+	*pserver_principal = server_principal;
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gse_context_init(TALLOC_CTX *mem_ctx,
+				 bool do_sign, bool do_seal,
+				 const char *ccache_name,
+				 uint32_t add_gss_c_flags,
+				 struct gse_context **_gse_ctx)
+{
+	struct gse_context *gse_ctx;
+	krb5_error_code k5ret;
+	NTSTATUS status;
+
+	gse_ctx = talloc_zero(mem_ctx, struct gse_context);
+	if (!gse_ctx) {
+		return NT_STATUS_NO_MEMORY;
+	}
+	talloc_set_destructor((TALLOC_CTX *)gse_ctx, gse_context_destructor);
+
+	gse_ctx->expire_time = GENSEC_EXPIRE_TIME_INFINITY;
+	gse_ctx->max_wrap_buf_size = UINT16_MAX;
+
+	memcpy(&gse_ctx->gss_mech, gss_mech_krb5, sizeof(gss_OID_desc));
+
+	gse_ctx->gss_want_flags = GSS_C_MUTUAL_FLAG |
+				GSS_C_DELEG_POLICY_FLAG |
+				GSS_C_REPLAY_FLAG |
+				GSS_C_SEQUENCE_FLAG;
+	if (do_sign) {
+		gse_ctx->gss_want_flags |= GSS_C_INTEG_FLAG;
+	}
+	if (do_seal) {
+		gse_ctx->gss_want_flags |= GSS_C_INTEG_FLAG;
+		gse_ctx->gss_want_flags |= GSS_C_CONF_FLAG;
+	}
+
+	gse_ctx->gss_want_flags |= add_gss_c_flags;
+
+	/* Initialize Kerberos Context */
+	k5ret = smb_krb5_init_context_common(&gse_ctx->k5ctx);
+	if (k5ret) {
+		DBG_ERR("kerberos init context failed (%s)\n",
+			error_message(k5ret));
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto err_out;
+	}
+
+#ifdef SAMBA4_USES_HEIMDAL
+	k5ret = gsskrb5_set_dns_canonicalize(false);
+	if (k5ret) {
+		DBG_ERR("gsskrb5_set_dns_canonicalize() failed (%s)\n",
+			error_message(k5ret));
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto err_out;
+	}
+#endif
+
+	if (!ccache_name) {
+		ccache_name = krb5_cc_default_name(gse_ctx->k5ctx);
+	}
+	k5ret = krb5_cc_resolve(gse_ctx->k5ctx, ccache_name,
+				&gse_ctx->ccache);
+	if (k5ret) {
+		DEBUG(1, ("Failed to resolve credential cache '%s'! (%s)\n",
+			  ccache_name, error_message(k5ret)));
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto err_out;
+	}
+
+	/* TODO: Should we enforce a enc_types list ?
+	ret = krb5_set_default_tgs_ktypes(gse_ctx->k5ctx, enc_types);
+	*/
+
+	*_gse_ctx = gse_ctx;
+	return NT_STATUS_OK;
+
+err_out:
+	TALLOC_FREE(gse_ctx);
+	return status;
+}
+
+static NTSTATUS gse_init_client(struct gensec_security *gensec_security,
+				bool do_sign, bool do_seal,
+				const char *ccache_name,
+				const char *server,
+				const char *service,
+				const char *realm,
+				const char *username,
+				const char *password,
+				uint32_t add_gss_c_flags,
+				struct gse_context **_gse_ctx)
+{
+	struct gse_context *gse_ctx;
+	OM_uint32 gss_maj, gss_min;
+#ifdef HAVE_GSS_KRB5_CRED_NO_CI_FLAGS_X
+	gss_buffer_desc empty_buffer = GSS_C_EMPTY_BUFFER;
+	gss_OID oid = discard_const(GSS_KRB5_CRED_NO_CI_FLAGS_X);
+#endif
+	NTSTATUS status;
+
+	if (!server || !service) {
+		return NT_STATUS_INVALID_PARAMETER;
+	}
+
+	status = gse_context_init(gensec_security, do_sign, do_seal,
+				  ccache_name, add_gss_c_flags,
+				  &gse_ctx);
+	if (!NT_STATUS_IS_OK(status)) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+#ifdef SAMBA4_USES_HEIMDAL
+	{
+		int ret;
+		bool set_dns_canon = gensec_setting_bool(
+				gensec_security->settings,
+				"krb5", "set_dns_canonicalize",
+				false);
+		const char *server_realm = lpcfg_realm(
+				gensec_security->settings->lp_ctx);
+		if (server_realm != NULL) {
+			ret = gsskrb5_set_default_realm(server_realm);
+			if (ret) {
+				DBG_ERR("gsskrb5_set_default_realm failed\n");
+				return NT_STATUS_INTERNAL_ERROR;
+			}
+		}
+
+		/*
+		 * don't do DNS lookups of any kind, it might/will
+		 * fail for a netbios name
+		 */
+		ret = gsskrb5_set_dns_canonicalize(set_dns_canon);
+		if (ret != GSS_S_COMPLETE) {
+			DBG_ERR("gsskrb5_set_dns_canonicalize failed\n");
+			return NT_STATUS_INTERNAL_ERROR;
+		}
+	}
+#endif
+
+	/* TODO: get krb5 ticket using username/password, if no valid
+	 * one already available in ccache */
+
+	gss_maj = smb_gss_krb5_import_cred(&gss_min,
+					   gse_ctx->k5ctx,
+					   gse_ctx->ccache,
+					   NULL, /* keytab_principal */
+					   NULL, /* keytab */
+					   &gse_ctx->creds);
+	if (gss_maj) {
+		char *ccache = NULL;
+		int kret;
+
+		kret = krb5_cc_get_full_name(gse_ctx->k5ctx,
+					     gse_ctx->ccache,
+					     &ccache);
+		if (kret != 0) {
+			ccache = NULL;
+		}
+
+		DEBUG(5, ("smb_gss_krb5_import_cred ccache[%s] failed with [%s] -"
+			  "the caller may retry after a kinit.\n",
+			  ccache, gse_errstr(gse_ctx, gss_maj, gss_min)));
+		krb5_free_string(gse_ctx->k5ctx, ccache);
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto err_out;
+	}
+
+#ifdef HAVE_GSS_KRB5_CRED_NO_CI_FLAGS_X
+	/*
+	 * Don't force GSS_C_CONF_FLAG and GSS_C_INTEG_FLAG.
+	 *
+	 * This allows us to disable SIGN and SEAL for
+	 * AUTH_LEVEL_CONNECT and AUTH_LEVEL_INTEGRITY.
+	 *
+	 * https://groups.yahoo.com/neo/groups/cat-ietf/conversations/topics/575
+	 * http://krbdev.mit.edu/rt/Ticket/Display.html?id=6938
+	 */
+	gss_maj = gss_set_cred_option(&gss_min, &gse_ctx->creds,
+				      oid,
+				      &empty_buffer);
+	if (gss_maj) {
+		DEBUG(0, ("gss_set_cred_option(GSS_KRB5_CRED_NO_CI_FLAGS_X), "
+			  "failed with [%s]\n",
+			  gse_errstr(gse_ctx, gss_maj, gss_min)));
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto err_out;
+	}
+#endif
+
+	*_gse_ctx = gse_ctx;
+	return NT_STATUS_OK;
+
+err_out:
+	TALLOC_FREE(gse_ctx);
+	return status;
+}
+
+static NTSTATUS gse_get_client_auth_token(TALLOC_CTX *mem_ctx,
+					  struct gensec_security *gensec_security,
+					  const DATA_BLOB *token_in,
+					  DATA_BLOB *token_out)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+				      struct gse_context);
+	OM_uint32 gss_maj = 0;
+	OM_uint32 gss_min;
+	gss_buffer_desc in_data;
+	gss_buffer_desc out_data;
+	DATA_BLOB blob = data_blob_null;
+	NTSTATUS status;
+	OM_uint32 time_rec = 0;
+	struct timeval tv;
+	struct cli_credentials *cli_creds = gensec_get_credentials(gensec_security);
+	const char *target_principal = gensec_get_target_principal(gensec_security);
+	const char *hostname = gensec_get_target_hostname(gensec_security);
+	const char *service = gensec_get_target_service(gensec_security);
+	const char *client_realm = cli_credentials_get_realm(cli_creds);
+	char *server_principal = NULL;
+	char *server_realm = NULL;
+	bool fallback = false;
+	OM_uint32 time_req = 0;
+
+	time_req = gensec_setting_int(gensec_security->settings,
+				      "gensec_gssapi",
+				      "requested_life_time",
+				      time_req);
+
+	in_data.value = token_in->data;
+	in_data.length = token_in->length;
+
+	/*
+	 * With credentials for administrator@FOREST1.EXAMPLE.COM this patch
+	 * changes the target_principal for the ldap service of host
+	 * dc2.forest2.example.com from
+	 *
+	 *   ldap/dc2.forest2.example.com@FOREST1.EXAMPLE.COM
+	 *
+	 * to
+	 *
+	 *   ldap/dc2.forest2.example.com@FOREST2.EXAMPLE.COM
+	 *
+	 * Typically ldap/dc2.forest2.example.com@FOREST1.EXAMPLE.COM should be
+	 * used in order to allow the KDC of FOREST1.EXAMPLE.COM to generate a
+	 * referral ticket for krbtgt/FOREST2.EXAMPLE.COM@FOREST1.EXAMPLE.COM.
+	 *
+	 * The problem is that KDCs only return such referral tickets if
+	 * there's a forest trust between FOREST1.EXAMPLE.COM and
+	 * FOREST2.EXAMPLE.COM. If there's only an external domain trust
+	 * between FOREST1.EXAMPLE.COM and FOREST2.EXAMPLE.COM the KDC of
+	 * FOREST1.EXAMPLE.COM will respond with S_PRINCIPAL_UNKNOWN when being
+	 * asked for ldap/dc2.forest2.example.com@FOREST1.EXAMPLE.COM.
+	 *
+	 * In the case of an external trust the client can still ask explicitly
+	 * for krbtgt/FOREST2.EXAMPLE.COM@FOREST1.EXAMPLE.COM and the KDC of
+	 * FOREST1.EXAMPLE.COM will generate it.
+	 *
+	 * From there the client can use the
+	 * krbtgt/FOREST2.EXAMPLE.COM@FOREST1.EXAMPLE.COM ticket and ask a KDC
+	 * of FOREST2.EXAMPLE.COM for a service ticket for
+	 * ldap/dc2.forest2.example.com@FOREST2.EXAMPLE.COM.
+	 *
+	 * With Heimdal we'll get the fallback on S_PRINCIPAL_UNKNOWN behavior
+	 * when we pass ldap/dc2.forest2.example.com@FOREST2.EXAMPLE.COM as
+	 * target principal. As _krb5_get_cred_kdc_any() first calls
+	 * get_cred_kdc_referral() (which always starts with the client realm)
+	 * and falls back to get_cred_kdc_capath() (which starts with the given
+	 * realm).
+	 *
+	 * MIT krb5 only tries the given realm of the target principal, if we
+	 * want to autodetect support for transitive forest trusts, would have
+	 * to do the fallback ourself.
+	 */
+#ifndef SAMBA4_USES_HEIMDAL
+	if (gse_ctx->server_name == NULL) {
+		OM_uint32 gss_min2 = 0;
+
+		status = gse_setup_server_principal(mem_ctx,
+						    target_principal,
+						    service,
+						    hostname,
+						    client_realm,
+						    &server_principal,
+						    &gse_ctx->server_name);
+		if (!NT_STATUS_IS_OK(status)) {
+			return status;
+		}
+
+		gss_maj = gss_init_sec_context(&gss_min,
+					       gse_ctx->creds,
+					       &gse_ctx->gssapi_context,
+					       gse_ctx->server_name,
+					       &gse_ctx->gss_mech,
+					       gse_ctx->gss_want_flags,
+					       time_req,
+					       GSS_C_NO_CHANNEL_BINDINGS,
+					       &in_data,
+					       NULL,
+					       &out_data,
+					       &gse_ctx->gss_got_flags,
+					       &time_rec);
+		if (gss_maj != GSS_S_FAILURE) {
+			goto init_sec_context_done;
+		}
+		if (gss_min != (OM_uint32)KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN) {
+			goto init_sec_context_done;
+		}
+		if (target_principal != NULL) {
+			goto init_sec_context_done;
+		}
+
+		fallback = true;
+		TALLOC_FREE(server_principal);
+		gss_release_name(&gss_min2, &gse_ctx->server_name);
+	}
+#endif /* !SAMBA4_USES_HEIMDAL */
+
+	if (gse_ctx->server_name == NULL) {
+		server_realm = smb_krb5_get_realm_from_hostname(mem_ctx,
+								hostname,
+								client_realm);
+		if (server_realm == NULL) {
+			return NT_STATUS_NO_MEMORY;
+		}
+
+		if (fallback &&
+		    strequal(client_realm, server_realm)) {
+			goto init_sec_context_done;
+		}
+
+		status = gse_setup_server_principal(mem_ctx,
+						    target_principal,
+						    service,
+						    hostname,
+						    server_realm,
+						    &server_principal,
+						    &gse_ctx->server_name);
+		TALLOC_FREE(server_realm);
+		if (!NT_STATUS_IS_OK(status)) {
+			return status;
+		}
+
+		TALLOC_FREE(server_principal);
+	}
+
+	gss_maj = gss_init_sec_context(&gss_min,
+					gse_ctx->creds,
+					&gse_ctx->gssapi_context,
+					gse_ctx->server_name,
+					&gse_ctx->gss_mech,
+					gse_ctx->gss_want_flags,
+					time_req, GSS_C_NO_CHANNEL_BINDINGS,
+					&in_data, NULL, &out_data,
+					&gse_ctx->gss_got_flags, &time_rec);
+	goto init_sec_context_done;
+	/* JUMP! */
+init_sec_context_done:
+
+	switch (gss_maj) {
+	case GSS_S_COMPLETE:
+		/* we are done with it */
+		tv = timeval_current_ofs(time_rec, 0);
+		gse_ctx->expire_time = timeval_to_nttime(&tv);
+
+		status = NT_STATUS_OK;
+		break;
+	case GSS_S_CONTINUE_NEEDED:
+		/* we will need a third leg */
+		status = NT_STATUS_MORE_PROCESSING_REQUIRED;
+		break;
+	case GSS_S_CONTEXT_EXPIRED:
+		/* Make SPNEGO ignore us, we can't go any further here */
+		DBG_NOTICE("Context expired\n");
+		status = NT_STATUS_INVALID_PARAMETER;
+		goto done;
+	case GSS_S_FAILURE:
+		switch (gss_min) {
+		case (OM_uint32)KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN: {
+			gss_buffer_desc name_token = {
+				.length = 0,
+			};
+
+			gss_maj = gss_display_name(&gss_min,
+						   gse_ctx->server_name,
+						   &name_token,
+						   NULL);
+			if (gss_maj == GSS_S_COMPLETE) {
+				DBG_NOTICE("Server principal %.*s not found\n",
+					   (int)name_token.length,
+					   (char *)name_token.value);
+				gss_release_buffer(&gss_maj, &name_token);
+			} else {
+				DBG_NOTICE("Server principal not found\n");
+			}
+
+			/* Make SPNEGO ignore us, we can't go any further here */
+			status = NT_STATUS_INVALID_PARAMETER;
+			goto done;
+		}
+		case (OM_uint32)KRB5KRB_AP_ERR_TKT_EXPIRED:
+			DBG_NOTICE("Ticket expired\n");
+			/* Make SPNEGO ignore us, we can't go any further here */
+			status = NT_STATUS_INVALID_PARAMETER;
+			goto done;
+		case (OM_uint32)KRB5KRB_AP_ERR_TKT_NYV:
+			DBG_NOTICE("Clockskew\n");
+			/* Make SPNEGO ignore us, we can't go any further here */
+			status = NT_STATUS_TIME_DIFFERENCE_AT_DC;
+			goto done;
+		case (OM_uint32)KRB5_KDC_UNREACH:
+			DBG_NOTICE("KDC unreachable\n");
+			/* Make SPNEGO ignore us, we can't go any further here */
+			status = NT_STATUS_NO_LOGON_SERVERS;
+			goto done;
+		case (OM_uint32)KRB5KRB_AP_ERR_MSG_TYPE:
+			/* Garbage input, possibly from the auto-mech detection */
+			status = NT_STATUS_INVALID_PARAMETER;
+			goto done;
+		case (OM_uint32)KRB5KDC_ERR_ETYPE_NOSUPP:
+			status = NT_STATUS_KDC_UNKNOWN_ETYPE;
+			goto done;
+		default:
+			DBG_ERR("gss_init_sec_context failed with [%s](%u)\n",
+				gse_errstr(talloc_tos(), gss_maj, gss_min),
+				gss_min);
+			status = NT_STATUS_LOGON_FAILURE;
+			goto done;
+		}
+		break;
+	default:
+		DBG_ERR("gss_init_sec_context failed with [%s]\n",
+			gse_errstr(talloc_tos(), gss_maj, gss_min));
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto done;
+	}
+
+	/* we may be told to return nothing */
+	if (out_data.length) {
+		blob = data_blob_talloc(mem_ctx, out_data.value, out_data.length);
+		if (!blob.data) {
+			status = NT_STATUS_NO_MEMORY;
+		}
+
+		gss_release_buffer(&gss_min, &out_data);
+	}
+
+done:
+	*token_out = blob;
+	return status;
+}
+
+static NTSTATUS gse_init_server(TALLOC_CTX *mem_ctx,
+				bool do_sign, bool do_seal,
+				uint32_t add_gss_c_flags,
+				struct gse_context **_gse_ctx)
+{
+	struct gse_context *gse_ctx;
+	OM_uint32 gss_maj, gss_min;
+	krb5_error_code ret;
+	NTSTATUS status;
+
+	status = gse_context_init(mem_ctx, do_sign, do_seal,
+				  NULL, add_gss_c_flags, &gse_ctx);
+	if (!NT_STATUS_IS_OK(status)) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	ret = gse_krb5_get_server_keytab(gse_ctx->k5ctx,
+					 &gse_ctx->keytab);
+	if (ret) {
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto done;
+	}
+
+	/* This creates a GSSAPI cred_id_t with the keytab set */
+	gss_maj = smb_gss_krb5_import_cred(&gss_min, gse_ctx->k5ctx,
+					   NULL, NULL, gse_ctx->keytab,
+					   &gse_ctx->creds);
+
+	if (gss_maj != 0) {
+		DEBUG(0, ("smb_gss_krb5_import_cred failed with [%s]\n",
+			  gse_errstr(gse_ctx, gss_maj, gss_min)));
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto done;
+	}
+
+	status = NT_STATUS_OK;
+
+done:
+	if (!NT_STATUS_IS_OK(status)) {
+		TALLOC_FREE(gse_ctx);
+	}
+
+	*_gse_ctx = gse_ctx;
+	return status;
+}
+
+static NTSTATUS gse_get_server_auth_token(TALLOC_CTX *mem_ctx,
+					  struct gensec_security *gensec_security,
+					  const DATA_BLOB *token_in,
+					  DATA_BLOB *token_out)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+				      struct gse_context);
+	OM_uint32 gss_maj, gss_min;
+	gss_buffer_desc in_data;
+	gss_buffer_desc out_data;
+	DATA_BLOB blob = data_blob_null;
+	NTSTATUS status;
+	OM_uint32 time_rec = 0;
+	struct timeval tv;
+
+	in_data.value = token_in->data;
+	in_data.length = token_in->length;
+
+	gss_maj = gss_accept_sec_context(&gss_min,
+					 &gse_ctx->gssapi_context,
+					 gse_ctx->creds,
+					 &in_data,
+					 GSS_C_NO_CHANNEL_BINDINGS,
+					 &gse_ctx->client_name,
+					 &gse_ctx->ret_mech,
+					 &out_data,
+					 &gse_ctx->gss_got_flags,
+					 &time_rec,
+					 &gse_ctx->delegated_cred_handle);
+	switch (gss_maj) {
+	case GSS_S_COMPLETE:
+		/* we are done with it */
+		tv = timeval_current_ofs(time_rec, 0);
+		gse_ctx->expire_time = timeval_to_nttime(&tv);
+
+		status = NT_STATUS_OK;
+		break;
+	case GSS_S_CONTINUE_NEEDED:
+		/* we will need a third leg */
+		status = NT_STATUS_MORE_PROCESSING_REQUIRED;
+		break;
+	default:
+		DEBUG(1, ("gss_accept_sec_context failed with [%s]\n",
+			  gse_errstr(talloc_tos(), gss_maj, gss_min)));
+
+		if (gse_ctx->gssapi_context) {
+			gss_delete_sec_context(&gss_min,
+						&gse_ctx->gssapi_context,
+						GSS_C_NO_BUFFER);
+		}
+
+		/*
+		 * If we got an output token, make Windows aware of it
+		 * by telling it that more processing is needed
+		 */
+		if (out_data.length > 0) {
+			status = NT_STATUS_MORE_PROCESSING_REQUIRED;
+			/* Fall through to handle the out token */
+		} else {
+			status = NT_STATUS_LOGON_FAILURE;
+			goto done;
+		}
+	}
+
+	/* we may be told to return nothing */
+	if (out_data.length) {
+		blob = data_blob_talloc(mem_ctx, out_data.value, out_data.length);
+		if (!blob.data) {
+			status = NT_STATUS_NO_MEMORY;
+		}
+		gss_release_buffer(&gss_min, &out_data);
+	}
+
+
+done:
+	*token_out = blob;
+	return status;
+}
+
+static char *gse_errstr(TALLOC_CTX *mem_ctx, OM_uint32 maj, OM_uint32 min)
+{
+	OM_uint32 gss_min, gss_maj;
+	gss_buffer_desc msg_min;
+	gss_buffer_desc msg_maj;
+	OM_uint32 msg_ctx = 0;
+
+	char *errstr = NULL;
+
+	ZERO_STRUCT(msg_min);
+	ZERO_STRUCT(msg_maj);
+
+	gss_maj = gss_display_status(&gss_min, maj, GSS_C_GSS_CODE,
+				     GSS_C_NO_OID, &msg_ctx, &msg_maj);
+	if (gss_maj) {
+		goto done;
+	}
+	errstr = talloc_strndup(mem_ctx,
+				(char *)msg_maj.value,
+					msg_maj.length);
+	if (!errstr) {
+		goto done;
+	}
+	gss_maj = gss_display_status(&gss_min, min, GSS_C_MECH_CODE,
+				     (gss_OID)discard_const(gss_mech_krb5),
+				     &msg_ctx, &msg_min);
+	if (gss_maj) {
+		goto done;
+	}
+
+	errstr = talloc_strdup_append_buffer(errstr, ": ");
+	if (!errstr) {
+		goto done;
+	}
+	errstr = talloc_strndup_append_buffer(errstr,
+						(char *)msg_min.value,
+							msg_min.length);
+	if (!errstr) {
+		goto done;
+	}
+
+done:
+	if (msg_min.value) {
+		gss_release_buffer(&gss_min, &msg_min);
+	}
+	if (msg_maj.value) {
+		gss_release_buffer(&gss_min, &msg_maj);
+	}
+	return errstr;
+}
+
+static NTSTATUS gensec_gse_client_start(struct gensec_security *gensec_security)
+{
+	struct gse_context *gse_ctx;
+	struct cli_credentials *creds = gensec_get_credentials(gensec_security);
+	NTSTATUS nt_status;
+	OM_uint32 want_flags = 0;
+	bool do_sign = false, do_seal = false;
+	const char *hostname = gensec_get_target_hostname(gensec_security);
+	const char *service = gensec_get_target_service(gensec_security);
+	const char *username = cli_credentials_get_username(creds);
+	const char *password = cli_credentials_get_password(creds);
+	const char *realm = cli_credentials_get_realm(creds);
+
+	if (!hostname) {
+		DEBUG(1, ("Could not determine hostname for target computer, cannot use kerberos\n"));
+		return NT_STATUS_INVALID_PARAMETER;
+	}
+	if (is_ipaddress(hostname)) {
+		DEBUG(2, ("Cannot do GSE to an IP address\n"));
+		return NT_STATUS_INVALID_PARAMETER;
+	}
+	if (strcmp(hostname, "localhost") == 0) {
+		DEBUG(2, ("GSE to 'localhost' does not make sense\n"));
+		return NT_STATUS_INVALID_PARAMETER;
+	}
+
+	if (gensec_security->want_features & GENSEC_FEATURE_SESSION_KEY) {
+		do_sign = true;
+	}
+	if (gensec_security->want_features & GENSEC_FEATURE_SIGN) {
+		do_sign = true;
+	}
+	if (gensec_security->want_features & GENSEC_FEATURE_SEAL) {
+		do_seal = true;
+	}
+	if (gensec_security->want_features & GENSEC_FEATURE_DCE_STYLE) {
+		want_flags |= GSS_C_DCE_STYLE;
+	}
+
+	nt_status = gse_init_client(gensec_security, do_sign, do_seal, NULL,
+				    hostname, service, realm,
+				    username, password, want_flags,
+				    &gse_ctx);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+		return nt_status;
+	}
+	gensec_security->private_data = gse_ctx;
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_server_start(struct gensec_security *gensec_security)
+{
+	struct gse_context *gse_ctx;
+	NTSTATUS nt_status;
+	OM_uint32 want_flags = 0;
+	bool do_sign = false, do_seal = false;
+
+	if (gensec_security->want_features & GENSEC_FEATURE_SIGN) {
+		do_sign = true;
+	}
+	if (gensec_security->want_features & GENSEC_FEATURE_SEAL) {
+		do_seal = true;
+	}
+	if (gensec_security->want_features & GENSEC_FEATURE_DCE_STYLE) {
+		want_flags |= GSS_C_DCE_STYLE;
+	}
+
+	nt_status = gse_init_server(gensec_security, do_sign, do_seal, want_flags,
+				    &gse_ctx);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+		return nt_status;
+	}
+	gensec_security->private_data = gse_ctx;
+	return NT_STATUS_OK;
+}
+
+struct gensec_gse_update_state {
+	NTSTATUS status;
+	DATA_BLOB out;
+};
+
+static NTSTATUS gensec_gse_update_internal(struct gensec_security *gensec_security,
+					   TALLOC_CTX *mem_ctx,
+					   const DATA_BLOB in,
+					   DATA_BLOB *out);
+
+static struct tevent_req *gensec_gse_update_send(TALLOC_CTX *mem_ctx,
+						 struct tevent_context *ev,
+						 struct gensec_security *gensec_security,
+						 const DATA_BLOB in)
+{
+	struct tevent_req *req = NULL;
+	struct gensec_gse_update_state *state = NULL;
+	NTSTATUS status;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct gensec_gse_update_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	status = gensec_gse_update_internal(gensec_security,
+					    state, in,
+					    &state->out);
+	state->status = status;
+	if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
+		tevent_req_done(req);
+		return tevent_req_post(req, ev);
+	}
+	if (tevent_req_nterror(req, status)) {
+		return tevent_req_post(req, ev);
+	}
+
+	tevent_req_done(req);
+	return tevent_req_post(req, ev);
+}
+
+static NTSTATUS gensec_gse_update_internal(struct gensec_security *gensec_security,
+					   TALLOC_CTX *mem_ctx,
+					   const DATA_BLOB in,
+					   DATA_BLOB *out)
+{
+	NTSTATUS status;
+
+	switch (gensec_security->gensec_role) {
+	case GENSEC_CLIENT:
+		status = gse_get_client_auth_token(mem_ctx,
+						   gensec_security,
+						   &in, out);
+		break;
+	case GENSEC_SERVER:
+		status = gse_get_server_auth_token(mem_ctx,
+						   gensec_security,
+						   &in, out);
+		break;
+	}
+	if (!NT_STATUS_IS_OK(status)) {
+		return status;
+	}
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_update_recv(struct tevent_req *req,
+				       TALLOC_CTX *out_mem_ctx,
+				       DATA_BLOB *out)
+{
+	struct gensec_gse_update_state *state =
+		tevent_req_data(req,
+		struct gensec_gse_update_state);
+	NTSTATUS status;
+
+	*out = data_blob_null;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		tevent_req_received(req);
+		return status;
+	}
+
+	*out = state->out;
+	talloc_steal(out_mem_ctx, state->out.data);
+	status = state->status;
+	tevent_req_received(req);
+	return status;
+}
+
+static NTSTATUS gensec_gse_wrap(struct gensec_security *gensec_security,
+				TALLOC_CTX *mem_ctx,
+				const DATA_BLOB *in,
+				DATA_BLOB *out)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	OM_uint32 maj_stat, min_stat;
+	gss_buffer_desc input_token, output_token;
+	int conf_state;
+	input_token.length = in->length;
+	input_token.value = in->data;
+
+	maj_stat = gss_wrap(&min_stat,
+			    gse_ctx->gssapi_context,
+			    gensec_have_feature(gensec_security, GENSEC_FEATURE_SEAL),
+			    GSS_C_QOP_DEFAULT,
+			    &input_token,
+			    &conf_state,
+			    &output_token);
+	if (GSS_ERROR(maj_stat)) {
+		DEBUG(0, ("gensec_gse_wrap: GSS Wrap failed: %s\n",
+			  gse_errstr(talloc_tos(), maj_stat, min_stat)));
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	*out = data_blob_talloc(mem_ctx, output_token.value, output_token.length);
+	gss_release_buffer(&min_stat, &output_token);
+
+	if (gensec_have_feature(gensec_security, GENSEC_FEATURE_SEAL)
+	    && !conf_state) {
+		return NT_STATUS_ACCESS_DENIED;
+	}
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_unwrap(struct gensec_security *gensec_security,
+				     TALLOC_CTX *mem_ctx,
+				     const DATA_BLOB *in,
+				     DATA_BLOB *out)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	OM_uint32 maj_stat, min_stat;
+	gss_buffer_desc input_token, output_token;
+	int conf_state;
+	gss_qop_t qop_state;
+	input_token.length = in->length;
+	input_token.value = in->data;
+
+	maj_stat = gss_unwrap(&min_stat,
+			      gse_ctx->gssapi_context,
+			      &input_token,
+			      &output_token,
+			      &conf_state,
+			      &qop_state);
+	if (GSS_ERROR(maj_stat)) {
+		DEBUG(0, ("gensec_gse_unwrap: GSS UnWrap failed: %s\n",
+			  gse_errstr(talloc_tos(), maj_stat, min_stat)));
+		return NT_STATUS_ACCESS_DENIED;
+	}
+
+	*out = data_blob_talloc(mem_ctx, output_token.value, output_token.length);
+	gss_release_buffer(&min_stat, &output_token);
+
+	if (gensec_have_feature(gensec_security, GENSEC_FEATURE_SEAL)
+	    && !conf_state) {
+		return NT_STATUS_ACCESS_DENIED;
+	}
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_seal_packet(struct gensec_security *gensec_security,
+				       TALLOC_CTX *mem_ctx,
+				       uint8_t *data, size_t length,
+				       const uint8_t *whole_pdu, size_t pdu_length,
+				       DATA_BLOB *sig)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	bool hdr_signing = false;
+	size_t sig_size = 0;
+	NTSTATUS status;
+
+	if (gensec_security->want_features & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		hdr_signing = true;
+	}
+
+	sig_size = gensec_gse_sig_size(gensec_security, length);
+
+	status = gssapi_seal_packet(gse_ctx->gssapi_context,
+				    &gse_ctx->gss_mech,
+				    hdr_signing, sig_size,
+				    data, length,
+				    whole_pdu, pdu_length,
+				    mem_ctx, sig);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0, ("gssapi_seal_packet(hdr_signing=%u,sig_size=%zu,"
+			  "data=%zu,pdu=%zu) failed: %s\n",
+			  hdr_signing, sig_size, length, pdu_length,
+			  nt_errstr(status)));
+		return status;
+	}
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_unseal_packet(struct gensec_security *gensec_security,
+					 uint8_t *data, size_t length,
+					 const uint8_t *whole_pdu, size_t pdu_length,
+					 const DATA_BLOB *sig)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	bool hdr_signing = false;
+	NTSTATUS status;
+
+	if (gensec_security->want_features & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		hdr_signing = true;
+	}
+
+	status = gssapi_unseal_packet(gse_ctx->gssapi_context,
+				      &gse_ctx->gss_mech,
+				      hdr_signing,
+				      data, length,
+				      whole_pdu, pdu_length,
+				      sig);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0, ("gssapi_unseal_packet(hdr_signing=%u,sig_size=%zu,"
+			  "data=%zu,pdu=%zu) failed: %s\n",
+			  hdr_signing, sig->length, length, pdu_length,
+			  nt_errstr(status)));
+		return status;
+	}
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_sign_packet(struct gensec_security *gensec_security,
+				       TALLOC_CTX *mem_ctx,
+				       const uint8_t *data, size_t length,
+				       const uint8_t *whole_pdu, size_t pdu_length,
+				       DATA_BLOB *sig)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	bool hdr_signing = false;
+	NTSTATUS status;
+
+	if (gensec_security->want_features & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		hdr_signing = true;
+	}
+
+	status = gssapi_sign_packet(gse_ctx->gssapi_context,
+				    &gse_ctx->gss_mech,
+				    hdr_signing,
+				    data, length,
+				    whole_pdu, pdu_length,
+				    mem_ctx, sig);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0, ("gssapi_sign_packet(hdr_signing=%u,"
+			  "data=%zu,pdu=%zu) failed: %s\n",
+			  hdr_signing, length, pdu_length,
+			  nt_errstr(status)));
+		return status;
+	}
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_gse_check_packet(struct gensec_security *gensec_security,
+					const uint8_t *data, size_t length,
+					const uint8_t *whole_pdu, size_t pdu_length,
+					const DATA_BLOB *sig)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	bool hdr_signing = false;
+	NTSTATUS status;
+
+	if (gensec_security->want_features & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		hdr_signing = true;
+	}
+
+	status = gssapi_check_packet(gse_ctx->gssapi_context,
+				     &gse_ctx->gss_mech,
+				     hdr_signing,
+				     data, length,
+				     whole_pdu, pdu_length,
+				     sig);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0, ("gssapi_check_packet(hdr_signing=%u,sig_size=%zu"
+			  "data=%zu,pdu=%zu) failed: %s\n",
+			  hdr_signing, sig->length, length, pdu_length,
+			  nt_errstr(status)));
+		return status;
+	}
+
+	return NT_STATUS_OK;
+}
+
+/* Try to figure out what features we actually got on the connection */
+static bool gensec_gse_have_feature(struct gensec_security *gensec_security,
+				    uint32_t feature)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+
+	if (feature & GENSEC_FEATURE_SESSION_KEY) {
+		return gse_ctx->gss_got_flags & GSS_C_INTEG_FLAG;
+	}
+	if (feature & GENSEC_FEATURE_SIGN) {
+		return gse_ctx->gss_got_flags & GSS_C_INTEG_FLAG;
+	}
+	if (feature & GENSEC_FEATURE_SEAL) {
+		return gse_ctx->gss_got_flags & GSS_C_CONF_FLAG;
+	}
+	if (feature & GENSEC_FEATURE_DCE_STYLE) {
+		return gse_ctx->gss_got_flags & GSS_C_DCE_STYLE;
+	}
+	if (feature & GENSEC_FEATURE_NEW_SPNEGO) {
+		NTSTATUS status;
+		uint32_t keytype;
+
+		if (!(gse_ctx->gss_got_flags & GSS_C_INTEG_FLAG)) {
+			return false;
+		}
+
+		status = gssapi_get_session_key(talloc_tos(),
+						gse_ctx->gssapi_context, NULL, &keytype);
+		/*
+		 * We should do a proper sig on the mechListMic unless
+		 * we know we have to be backwards compatible with
+		 * earlier windows versions.
+		 *
+		 * Negotiating a non-krb5
+		 * mech for example should be regarded as having
+		 * NEW_SPNEGO
+		 */
+		if (NT_STATUS_IS_OK(status)) {
+			switch (keytype) {
+			case ENCTYPE_DES_CBC_CRC:
+			case ENCTYPE_DES_CBC_MD5:
+			case ENCTYPE_ARCFOUR_HMAC:
+			case ENCTYPE_DES3_CBC_SHA1:
+				return false;
+			}
+		}
+		return true;
+	}
+	/* We can always do async (rather than strict request/reply) packets.  */
+	if (feature & GENSEC_FEATURE_ASYNC_REPLIES) {
+		return true;
+	}
+	if (feature & GENSEC_FEATURE_SIGN_PKT_HEADER) {
+		return true;
+	}
+	return false;
+}
+
+static NTTIME gensec_gse_expire_time(struct gensec_security *gensec_security)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+
+	return gse_ctx->expire_time;
+}
+
+/*
+ * Extract the 'session key' needed by SMB signing and ncacn_np
+ * (for encrypting some passwords).
+ *
+ * This breaks all the abstractions, but what do you expect...
+ */
+static NTSTATUS gensec_gse_session_key(struct gensec_security *gensec_security,
+				       TALLOC_CTX *mem_ctx,
+				       DATA_BLOB *session_key)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+
+	return gssapi_get_session_key(mem_ctx, gse_ctx->gssapi_context, session_key, NULL);
+}
+
+/* Get some basic (and authorization) information about the user on
+ * this session.  This uses either the PAC (if present) or a local
+ * database lookup */
+static NTSTATUS gensec_gse_session_info(struct gensec_security *gensec_security,
+					TALLOC_CTX *mem_ctx,
+					struct auth_session_info **_session_info)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	NTSTATUS nt_status;
+	TALLOC_CTX *tmp_ctx;
+	struct auth_session_info *session_info = NULL;
+	OM_uint32 maj_stat, min_stat;
+	DATA_BLOB pac_blob, *pac_blob_ptr = NULL;
+
+	gss_buffer_desc name_token;
+	char *principal_string;
+
+	tmp_ctx = talloc_named(mem_ctx, 0, "gensec_gse_session_info context");
+	NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
+
+	maj_stat = gss_display_name(&min_stat,
+				    gse_ctx->client_name,
+				    &name_token,
+				    NULL);
+	if (GSS_ERROR(maj_stat)) {
+		DEBUG(1, ("GSS display_name failed: %s\n",
+			  gse_errstr(talloc_tos(), maj_stat, min_stat)));
+		talloc_free(tmp_ctx);
+		return NT_STATUS_FOOBAR;
+	}
+
+	principal_string = talloc_strndup(tmp_ctx,
+					  (const char *)name_token.value,
+					  name_token.length);
+
+	gss_release_buffer(&min_stat, &name_token);
+
+	if (!principal_string) {
+		talloc_free(tmp_ctx);
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	nt_status = gssapi_obtain_pac_blob(tmp_ctx,  gse_ctx->gssapi_context,
+					   gse_ctx->client_name,
+					   &pac_blob);
+
+	/* IF we have the PAC - otherwise we need to get this
+	 * data from elsewhere
+	 */
+	if (NT_STATUS_IS_OK(nt_status)) {
+		pac_blob_ptr = &pac_blob;
+	}
+	nt_status = gensec_generate_session_info_pac(tmp_ctx,
+						     gensec_security,
+						     NULL,
+						     pac_blob_ptr, principal_string,
+						     gensec_get_remote_address(gensec_security),
+						     &session_info);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+		talloc_free(tmp_ctx);
+		return nt_status;
+	}
+
+	nt_status = gensec_gse_session_key(gensec_security, session_info,
+					   &session_info->session_key);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+		talloc_free(tmp_ctx);
+		return nt_status;
+	}
+
+	*_session_info = talloc_move(mem_ctx, &session_info);
+	talloc_free(tmp_ctx);
+
+	return NT_STATUS_OK;
+}
+
+static size_t gensec_gse_max_input_size(struct gensec_security *gensec_security)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	OM_uint32 maj_stat, min_stat;
+	OM_uint32 max_input_size;
+
+	maj_stat = gss_wrap_size_limit(&min_stat,
+				       gse_ctx->gssapi_context,
+				       gensec_have_feature(gensec_security, GENSEC_FEATURE_SEAL),
+				       GSS_C_QOP_DEFAULT,
+				       gse_ctx->max_wrap_buf_size,
+				       &max_input_size);
+	if (GSS_ERROR(maj_stat)) {
+		TALLOC_CTX *mem_ctx = talloc_new(NULL);
+		DEBUG(1, ("gensec_gssapi_max_input_size: determining signature size with gss_wrap_size_limit failed: %s\n",
+			  gse_errstr(mem_ctx, maj_stat, min_stat)));
+		talloc_free(mem_ctx);
+		return 0;
+	}
+
+	return max_input_size;
+}
+
+/* Find out the maximum output size negotiated on this connection */
+static size_t gensec_gse_max_wrapped_size(struct gensec_security *gensec_security)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+	return gse_ctx->max_wrap_buf_size;
+}
+
+static size_t gensec_gse_sig_size(struct gensec_security *gensec_security,
+				  size_t data_size)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+
+	if (gse_ctx->sig_size > 0) {
+		return gse_ctx->sig_size;
+	}
+
+	gse_ctx->sig_size = gssapi_get_sig_size(gse_ctx->gssapi_context,
+					        &gse_ctx->gss_mech,
+					        gse_ctx->gss_got_flags,
+					        data_size);
+	return gse_ctx->sig_size;
+}
+
+static const char *gensec_gse_final_auth_type(struct gensec_security *gensec_security)
+{
+	struct gse_context *gse_ctx =
+		talloc_get_type_abort(gensec_security->private_data,
+		struct gse_context);
+
+	/* Only return the string for GSSAPI/Krb5 */
+	if (smb_gss_oid_equal(&gse_ctx->gss_mech,
+			      gss_mech_krb5)) {
+		return GENSEC_FINAL_AUTH_TYPE_KRB5;
+	} else {
+		return "gensec_gse: UNKNOWN MECH";
+	}
+}
+
+static const char *gensec_gse_krb5_oids[] = {
+	GENSEC_OID_KERBEROS5_OLD,
+	GENSEC_OID_KERBEROS5,
+	NULL
+};
+
+const struct gensec_security_ops gensec_gse_krb5_security_ops = {
+	.name		= "gse_krb5",
+	.auth_type	= DCERPC_AUTH_TYPE_KRB5,
+	.oid            = gensec_gse_krb5_oids,
+	.client_start   = gensec_gse_client_start,
+	.server_start   = gensec_gse_server_start,
+	.magic  	= gensec_magic_check_krb5_oid,
+	.update_send	= gensec_gse_update_send,
+	.update_recv	= gensec_gse_update_recv,
+	.session_key	= gensec_gse_session_key,
+	.session_info	= gensec_gse_session_info,
+	.sig_size	= gensec_gse_sig_size,
+	.sign_packet	= gensec_gse_sign_packet,
+	.check_packet	= gensec_gse_check_packet,
+	.seal_packet	= gensec_gse_seal_packet,
+	.unseal_packet	= gensec_gse_unseal_packet,
+	.max_input_size	  = gensec_gse_max_input_size,
+	.max_wrapped_size = gensec_gse_max_wrapped_size,
+	.wrap           = gensec_gse_wrap,
+	.unwrap         = gensec_gse_unwrap,
+	.have_feature   = gensec_gse_have_feature,
+	.expire_time    = gensec_gse_expire_time,
+	.final_auth_type  = gensec_gse_final_auth_type,
+	.enabled        = true,
+	.kerberos       = true,
+	.priority       = GENSEC_GSSAPI
+};
+
+#endif /* HAVE_KRB5 */