r1437: Intermediate commit of krb5 for GENSEC.

The session key in the client is wrong, we don't do signing/sealing
and we are sending raw Kerberos, not GSSAPI.

But it's a start, and if we continue to have to call Krb5 directly,
this will be the basis.

I also intend to provide an alternate implementation, using just
GSSAPI.

Andrew Bartlett
(This used to be commit eb0dd4a821dc3dbe370aea9a9c9fb05cf2592e4d)

1 files changed, 351 insertions, 0 deletions

diff --git a/source4/libcli/auth/gensec_krb5.c b/source4/libcli/auth/gensec_krb5.c
new file mode 100644
index 0000000000..2035a5bf9a
--- /dev/null
+++ b/source4/libcli/auth/gensec_krb5.c
@@ -0,0 +1,351 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   Kerberos backend for GENSEC
+   
+   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004
+   Copyright (C) Andrew Tridgell 2001
+   Copyright (C) Luke Howard 2002-2003
+
+   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 2 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+#undef DBGC_CLASS
+#define DBGC_CLASS DBGC_AUTH
+
+enum GENSEC_KRB5_STATE {
+	GENSEC_KRB5_SERVER_START,
+	GENSEC_KRB5_CLIENT_START,
+	GENSEC_KRB5_CLIENT_MUTUAL_AUTH,
+	GENSEC_KRB5_DONE
+};
+
+struct gensec_krb5_state {
+	TALLOC_CTX *mem_ctx;
+	DATA_BLOB session_key;
+	DATA_BLOB pac;
+	enum GENSEC_KRB5_STATE state_position;
+	krb5_context krb5_context;
+	krb5_auth_context krb5_auth_context;
+};
+
+static NTSTATUS gensec_krb5_start(struct gensec_security *gensec_security)
+{
+	struct gensec_krb5_state *gensec_krb5_state;
+	krb5_error_code ret = 0;
+
+	TALLOC_CTX *mem_ctx = talloc_init("gensec_krb5");
+	if (!mem_ctx) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	gensec_krb5_state = talloc_p(mem_ctx, struct gensec_krb5_state);
+	if (!gensec_krb5_state) {
+		return NT_STATUS_NO_MEMORY;
+	}
+
+	gensec_krb5_state->mem_ctx = mem_ctx;
+
+	gensec_security->private_data = gensec_krb5_state;
+
+	initialize_krb5_error_table();
+	gensec_krb5_state->krb5_context = NULL;
+	gensec_krb5_state->krb5_auth_context = NULL;
+	gensec_krb5_state->session_key = data_blob(NULL, 0);
+
+	ret = krb5_init_context(&gensec_krb5_state->krb5_context);
+	if (ret) {
+		DEBUG(1,("gensec_krb5_start: krb5_init_context failed (%s)\n", error_message(ret)));
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+
+	if (lp_realm() && *lp_realm()) {
+		ret = krb5_set_default_realm(gensec_krb5_state->krb5_context, lp_realm());
+		if (ret) {
+			DEBUG(1,("gensec_krb5_start: krb5_set_default_realm failed (%s)\n", error_message(ret)));
+			return NT_STATUS_INTERNAL_ERROR;
+		}
+	}
+
+	ret = krb5_auth_con_init(gensec_krb5_state->krb5_context, &gensec_krb5_state->krb5_auth_context);
+	if (ret) {
+		DEBUG(1,("gensec_krb5_start: krb5_auth_con_init failed (%s)\n", error_message(ret)));
+		return NT_STATUS_INTERNAL_ERROR;
+	}
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_krb5_server_start(struct gensec_security *gensec_security)
+{
+	NTSTATUS nt_status;
+	struct gensec_krb5_state *gensec_krb5_state;
+
+	nt_status = gensec_krb5_start(gensec_security);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+		return nt_status;
+	}
+
+	gensec_krb5_state = gensec_security->private_data;
+	gensec_krb5_state->state_position = GENSEC_KRB5_SERVER_START;
+
+	return NT_STATUS_OK;
+}
+
+static NTSTATUS gensec_krb5_client_start(struct gensec_security *gensec_security)
+{
+	struct gensec_krb5_state *gensec_krb5_state;
+	
+	NTSTATUS nt_status;
+	nt_status = gensec_krb5_start(gensec_security);
+	if (!NT_STATUS_IS_OK(nt_status)) {
+		return nt_status;
+	}
+
+	gensec_krb5_state = gensec_security->private_data;
+	gensec_krb5_state->state_position = GENSEC_KRB5_CLIENT_START;
+
+	return NT_STATUS_OK;
+}
+
+static void gensec_krb5_end(struct gensec_security *gensec_security)
+{
+	struct gensec_krb5_state *gensec_krb5_state = gensec_security->private_data;
+
+	if (gensec_krb5_state->krb5_auth_context) {
+		krb5_auth_con_free(gensec_krb5_state->krb5_context, 
+				   gensec_krb5_state->krb5_auth_context);
+	}
+
+	if (gensec_krb5_state->krb5_context) {
+		krb5_free_context(gensec_krb5_state->krb5_context);
+	}
+
+	talloc_destroy(gensec_krb5_state->mem_ctx);
+	gensec_security->private_data = NULL;
+}
+
+
+/**
+ * Next state function for the Krb5 GENSEC mechanism
+ * 
+ * @param gensec_krb5_state KRB5 State
+ * @param out_mem_ctx The TALLOC_CTX for *out to be allocated on
+ * @param in The request, as a DATA_BLOB
+ * @param out The reply, as an talloc()ed DATA_BLOB, on *out_mem_ctx
+ * @return Error, MORE_PROCESSING_REQUIRED if a reply is sent, 
+ *                or NT_STATUS_OK if the user is authenticated. 
+ */
+
+static NTSTATUS gensec_krb5_update(struct gensec_security *gensec_security, TALLOC_CTX *out_mem_ctx, 
+				      const DATA_BLOB in, DATA_BLOB *out) 
+{
+	struct gensec_krb5_state *gensec_krb5_state = gensec_security->private_data;
+	krb5_error_code ret = 0;
+	DATA_BLOB pac;
+	NTSTATUS nt_status;
+
+	switch (gensec_krb5_state->state_position) {
+	case GENSEC_KRB5_CLIENT_START:
+	{
+		krb5_data packet;
+		krb5_ccache ccdef = NULL;
+		
+#if 0 /* When we get some way to input the time offset */
+		if (time_offset != 0) {
+			krb5_set_real_time(context, time(NULL) + time_offset, 0);
+		}
+#endif
+
+		ret = krb5_cc_default(gensec_krb5_state->krb5_context, &ccdef);
+		if (ret) {
+			DEBUG(1,("krb5_cc_default failed (%s)\n",
+				 error_message(ret)));
+			return NT_STATUS_INTERNAL_ERROR;
+		}
+
+		ret = ads_krb5_mk_req(gensec_krb5_state->krb5_context, 
+				      &gensec_krb5_state->krb5_auth_context, 
+				      AP_OPTS_USE_SUBKEY
+#ifdef MUTUAL_AUTH
+ | AP_OPTS_MUTUAL_REQUIRED
+#endif
+				      , 
+				      gensec_security->target.principal,
+				      ccdef, &packet);
+		if (ret) {
+			DEBUG(1,("ads_krb5_mk_req (request ticket) failed (%s)\n",
+				 error_message(ret)));
+			nt_status = NT_STATUS_LOGON_FAILURE;
+		} else {
+			*out = data_blob_talloc(out_mem_ctx, packet.data, packet.length);
+			
+			/* Hmm, heimdal dooesn't have this - what's the correct call? */
+#ifdef HAVE_KRB5_FREE_DATA_CONTENTS
+			krb5_free_data_contents(gensec_krb5_state->krb5_context, &packet); 
+#endif
+#ifdef MUTUAL_AUTH
+			gensec_krb5_state->state_position = GENSEC_KRB5_CLIENT_MUTUAL_AUTH;
+			nt_status = NT_STATUS_MORE_PROCESSING_REQUIRED;
+#else 
+			gensec_krb5_state->state_position = GENSEC_KRB5_DONE;
+			nt_status = NT_STATUS_OK;
+#endif
+		}
+		
+		/* Removed by jra. They really need to fix their kerberos so we don't leak memory. 
+		   JERRY -- disabled since it causes heimdal 0.6.1rc3 to die
+		   SuSE 9.1 Pro 
+		*/
+#if 0 /* redisabled by gd :) at least until any official heimdal version has it fixed. */
+		krb5_cc_close(context, ccdef);
+#endif
+		return nt_status;
+	}
+		
+	case GENSEC_KRB5_CLIENT_MUTUAL_AUTH:
+	{
+		krb5_data inbuf;
+		krb5_ap_rep_enc_part *repl = NULL;
+		inbuf.data = in.data;
+		inbuf.length = in.length;
+		ret = krb5_rd_rep(gensec_krb5_state->krb5_context, 
+				  gensec_krb5_state->krb5_auth_context,
+				  &inbuf, &repl);
+		if (ret) {
+			DEBUG(1,("krb5_rd_rep (mutual authentication) failed (%s)\n",
+				 error_message(ret)));
+			dump_data_pw("Mutual authentication message:\n", in.data, in.length);
+			nt_status = NT_STATUS_ACCESS_DENIED;
+		} else {
+			*out = data_blob(NULL, 0);
+			nt_status = NT_STATUS_OK;
+			gensec_krb5_state->state_position = GENSEC_KRB5_DONE;
+		}
+		if (repl) {
+			krb5_free_ap_rep_enc_part(gensec_krb5_state->krb5_context, repl);
+		}
+		return nt_status;
+	}
+		
+	case GENSEC_KRB5_SERVER_START:
+	{
+		char *principal;
+
+		nt_status = ads_verify_ticket(out_mem_ctx, 
+					      gensec_krb5_state->krb5_context, 
+					      gensec_krb5_state->krb5_auth_context, 
+					      lp_realm(), &in, 
+					      &principal, &pac, out);
+		gensec_krb5_state->pac = data_blob_talloc_steal(out_mem_ctx, gensec_krb5_state->mem_ctx, 
+								&pac);
+		/* TODO: parse the pac */
+
+		if (NT_STATUS_IS_OK(nt_status)) {
+			gensec_krb5_state->state_position = GENSEC_KRB5_DONE;
+		}
+		SAFE_FREE(principal);
+		return nt_status;
+	}
+	case GENSEC_KRB5_DONE:
+		return NT_STATUS_OK;
+	}
+	
+	return NT_STATUS_INVALID_PARAMETER;
+}
+
+static NTSTATUS gensec_krb5_session_key(struct gensec_security *gensec_security, 
+					   DATA_BLOB *session_key) 
+{
+	struct gensec_krb5_state *gensec_krb5_state = gensec_security->private_data;
+	krb5_context context = gensec_krb5_state->krb5_context;
+	krb5_auth_context auth_context = gensec_krb5_state->krb5_auth_context;
+	krb5_keyblock *skey;
+	krb5_error_code err;
+
+	if (gensec_krb5_state->session_key.data) {
+		*session_key = gensec_krb5_state->session_key;
+		return NT_STATUS_OK;
+	}
+
+	switch (gensec_security->gensec_role) {
+	case GENSEC_CLIENT:
+		err = krb5_auth_con_getlocalsubkey(context, auth_context, &skey);
+		break;
+	case GENSEC_SERVER:
+		err = krb5_auth_con_getremotesubkey(context, auth_context, &skey);
+		break;
+	}
+	if (err == 0 && skey != NULL) {
+		DEBUG(10, ("Got KRB5 session key of length %d\n",  KRB5_KEY_LENGTH(skey)));
+		gensec_krb5_state->session_key = data_blob_talloc(gensec_krb5_state->mem_ctx, 
+						KRB5_KEY_DATA(skey), KRB5_KEY_LENGTH(skey));
+		*session_key = gensec_krb5_state->session_key;
+		dump_data_pw("KRB5 Session Key:\n", session_key->data, session_key->length);
+
+		krb5_free_keyblock(context, skey);
+		return NT_STATUS_OK;
+	} else {
+		DEBUG(10, ("KRB5 error getting session key %d\n", err));
+		return NT_STATUS_NO_USER_SESSION_KEY;
+	}
+}
+
+
+static const struct gensec_security_ops gensec_krb5_security_ops = {
+	.name		= "krb5",
+	.auth_type	= DCERPC_AUTH_TYPE_KRB5,
+	.oid            = OID_KERBEROS5,
+	.client_start   = gensec_krb5_client_start,
+	.server_start   = gensec_krb5_server_start,
+	.update 	= gensec_krb5_update,
+	.session_key	= gensec_krb5_session_key,
+	.end		= gensec_krb5_end
+};
+
+static const struct gensec_security_ops gensec_ms_krb5_security_ops = {
+	.name		= "ms_krb5",
+	.auth_type	= DCERPC_AUTH_TYPE_KRB5,
+	.oid            = OID_KERBEROS5_OLD,
+	.client_start   = gensec_krb5_client_start,
+	.server_start   = gensec_krb5_server_start,
+	.update 	= gensec_krb5_update,
+	.session_key	= gensec_krb5_session_key,
+	.end		= gensec_krb5_end
+};
+
+
+NTSTATUS gensec_krb5_init(void)
+{
+	NTSTATUS ret;
+	ret = register_backend("gensec", &gensec_krb5_security_ops);
+	if (!NT_STATUS_IS_OK(ret)) {
+		DEBUG(0,("Failed to register '%s' gensec backend!\n",
+			gensec_krb5_security_ops.name));
+		return ret;
+	}
+
+	ret = register_backend("gensec", &gensec_ms_krb5_security_ops);
+	if (!NT_STATUS_IS_OK(ret)) {
+		DEBUG(0,("Failed to register '%s' gensec backend!\n",
+			gensec_krb5_security_ops.name));
+		return ret;
+	}
+
+	return ret;
+}