kpasswdd.c

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			krb5_free_principal(context, principal);
			return kpasswdd_make_error_reply(kdc, mem_ctx, 
							KRB5_KPASSWD_MALFORMED,
							"krb5_unparse_name failed!",
							reply);
		}
		
		krb5_free_principal(context, principal);
		
		samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx, session_info);
		if (!samdb) {
			return kpasswdd_make_error_reply(kdc, mem_ctx, 
							 KRB5_KPASSWD_HARDERROR,
							 "Unable to open database!",
							 reply);
		}

		DEBUG(3, ("%s\\%s (%s) is changing password of %s\n", 
			  session_info->server_info->domain_name,
			  session_info->server_info->account_name,
			  dom_sid_string(mem_ctx, session_info->security_token->user_sid), 
			  set_password_on_princ));
		ret = ldb_transaction_start(samdb);
		if (ret) {
			status = NT_STATUS_TRANSACTION_ABORTED;
			return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
							   status,
							   SAMR_REJECT_OTHER, 
							   NULL, 
							   reply);
		}

		status = crack_user_principal_name(samdb, mem_ctx, 
						   set_password_on_princ, 
						   &set_password_on_dn, NULL);
		free(set_password_on_princ);
		if (!NT_STATUS_IS_OK(status)) {
			ldb_transaction_cancel(samdb);
			return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
							   status,
							   SAMR_REJECT_OTHER, 
							   NULL, 
							   reply);
		}

		msg = ldb_msg_new(mem_ctx);
		if (msg == NULL) {
			ldb_transaction_cancel(samdb);
			status = NT_STATUS_NO_MEMORY;
		} else {
			msg->dn = ldb_dn_copy(msg, set_password_on_dn);
			if (!msg->dn) {
				status = NT_STATUS_NO_MEMORY;
			}
		}

		if (NT_STATUS_IS_OK(status)) {
			/* Admin password set */
			status = samdb_set_password(samdb, mem_ctx,
						    set_password_on_dn, NULL,
						    msg, password, NULL, NULL, 
						    false, /* this is not a user password change */
						    &reject_reason, &dominfo);
		}

		if (NT_STATUS_IS_OK(status)) {
			/* modify the samdb record */
			ret = samdb_replace(samdb, mem_ctx, msg);
			if (ret != 0) {
				DEBUG(2,("Failed to modify record to set password on %s: %s\n",
					 ldb_dn_get_linearized(msg->dn),
					 ldb_errstring(samdb)));
				status = NT_STATUS_ACCESS_DENIED;
			}
		}
		if (NT_STATUS_IS_OK(status)) {
			ret = ldb_transaction_commit(samdb);
			if (ret != 0) {
				DEBUG(1,("Failed to commit transaction to set password on %s: %s\n",
					 ldb_dn_get_linearized(msg->dn),
					 ldb_errstring(samdb)));
				status = NT_STATUS_TRANSACTION_ABORTED;
			}
		} else {
			ldb_transaction_cancel(samdb);
		}
		return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
						   status,
						   reject_reason, 
						   dominfo, 
						   reply);
	}
	default:
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						 KRB5_KPASSWD_BAD_VERSION,
						 talloc_asprintf(mem_ctx, 
								 "Protocol version %u not supported", 
								 version),
						 reply);
	}
	return true;
}

bool kpasswdd_process(struct kdc_server *kdc,
		      TALLOC_CTX *mem_ctx, 
		      DATA_BLOB *input, 
		      DATA_BLOB *reply,
		      struct socket_address *peer_addr,
		      struct socket_address *my_addr,
		      int datagram_reply)
{
	bool ret;
	const uint16_t header_len = 6;
	uint16_t len;
	uint16_t ap_req_len;
	uint16_t krb_priv_len;
	uint16_t version;
	NTSTATUS nt_status;
	DATA_BLOB ap_req, krb_priv_req;
	DATA_BLOB krb_priv_rep = data_blob(NULL, 0);
	DATA_BLOB ap_rep = data_blob(NULL, 0);
	DATA_BLOB kpasswd_req, kpasswd_rep;
	struct cli_credentials *server_credentials;
	struct gensec_security *gensec_security;
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	
	if (!tmp_ctx) {
		return false;
	}

	/* Be parinoid.  We need to ensure we don't just let the
	 * caller lead us into a buffer overflow */
	if (input->length <= header_len) {
		talloc_free(tmp_ctx);
		return false;
	}

	len = RSVAL(input->data, 0);
	if (input->length != len) {
		talloc_free(tmp_ctx);
		return false;
	}

	/* There are two different versions of this protocol so far,
	 * plus others in the standards pipe.  Fortunetly they all
	 * take a very similar framing */
	version = RSVAL(input->data, 2);
	ap_req_len = RSVAL(input->data, 4);
	if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
		talloc_free(tmp_ctx);
		return false;
	}
	
	krb_priv_len = len - ap_req_len;
	ap_req = data_blob_const(&input->data[header_len], ap_req_len);
	krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
	
	nt_status = gensec_server_start(tmp_ctx, kdc->task->event_ctx, kdc->task->lp_ctx, kdc->task->msg_ctx, &gensec_security);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return false;
	}

	server_credentials = cli_credentials_init(tmp_ctx);
	if (!server_credentials) {
		DEBUG(1, ("Failed to init server credentials\n"));
		return false;
	}

	/* We want the credentials subsystem to use the krb5 context
	 * we already have, rather than a new context */	
	cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
	cli_credentials_set_conf(server_credentials, kdc->task->lp_ctx);
	nt_status = cli_credentials_set_stored_principal(server_credentials, kdc->task->event_ctx, kdc->task->lp_ctx, "kadmin/changepw");
	if (!NT_STATUS_IS_OK(nt_status)) {
		ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
						       KRB5_KPASSWD_HARDERROR,
						       talloc_asprintf(mem_ctx, 
								       "Failed to obtain server credentials for kadmin/changepw: %s\n", 
								       nt_errstr(nt_status)),
						       &krb_priv_rep);
		ap_rep.length = 0;
		if (ret) {
			goto reply;
		}
		talloc_free(tmp_ctx);
		return ret;
	}
	
	nt_status = gensec_set_credentials(gensec_security, server_credentials);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return false;
	}

	/* The kerberos PRIV packets include these addresses.  MIT
	 * clients check that they are present */
	nt_status = gensec_set_peer_addr(gensec_security, peer_addr);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return false;
	}
	nt_status = gensec_set_my_addr(gensec_security, my_addr);
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return false;
	}

	/* We want the GENSEC wrap calls to generate PRIV tokens */
	gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);

	nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
	if (!NT_STATUS_IS_OK(nt_status)) {
		talloc_free(tmp_ctx);
		return false;
	}

	/* Accept the AP-REQ and generate teh AP-REP we need for the reply */
	nt_status = gensec_update(gensec_security, tmp_ctx, ap_req, &ap_rep);
	if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
		
		ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
						       KRB5_KPASSWD_HARDERROR,
						       talloc_asprintf(mem_ctx, 
								       "gensec_update failed: %s", 
								       nt_errstr(nt_status)),
						       &krb_priv_rep);
		ap_rep.length = 0;
		if (ret) {
			goto reply;
		}
		talloc_free(tmp_ctx);
		return ret;
	}

	/* Extract the data from the KRB-PRIV half of the message */
	nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
	if (!NT_STATUS_IS_OK(nt_status)) {
		ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
						       KRB5_KPASSWD_HARDERROR,
						       talloc_asprintf(mem_ctx, 
								       "gensec_unwrap failed: %s", 
								       nt_errstr(nt_status)),
						       &krb_priv_rep);
		ap_rep.length = 0;
		if (ret) {
			goto reply;
		}
		talloc_free(tmp_ctx);
		return ret;
	}

	/* Figure out something to do with it (probably changing a password...) */
	ret = kpasswd_process_request(kdc, tmp_ctx, 
				      gensec_security, 
				      version, 
				      &kpasswd_req, &kpasswd_rep); 
	if (!ret) {
		/* Argh! */
		return false;
	}

	/* And wrap up the reply: This ensures that the error message
	 * or success can be verified by the client */
	nt_status = gensec_wrap(gensec_security, tmp_ctx, 
				&kpasswd_rep, &krb_priv_rep);
	if (!NT_STATUS_IS_OK(nt_status)) {
		ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
						       KRB5_KPASSWD_HARDERROR,
						       talloc_asprintf(mem_ctx, 
								       "gensec_wrap failed: %s", 
								       nt_errstr(nt_status)),
						       &krb_priv_rep);
		ap_rep.length = 0;
		if (ret) {
			goto reply;
		}
		talloc_free(tmp_ctx);
		return ret;
	}
	
reply:
	*reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
	if (!reply->data) {
		return false;
	}

	RSSVAL(reply->data, 0, reply->length);
	RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
	RSSVAL(reply->data, 4, ap_rep.length);
	memcpy(reply->data + header_len, 
	       ap_rep.data, 
	       ap_rep.length);
	memcpy(reply->data + header_len + ap_rep.length, 
	       krb_priv_rep.data, 
	       krb_priv_rep.length);

	talloc_free(tmp_ctx);
	return ret;
}