kpasswdd.c

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/* 
   Unix SMB/CIFS implementation.

   kpasswd Server implementation

   Copyright (C) Andrew Bartlett <[e-mail]> 2005
   Copyright (C) Andrew Tridgell	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/>.
*/

#include "includes.h"
#include "smbd/service_task.h"
#include "lib/events/events.h"
#include "lib/socket/socket.h"
#include "kdc/kdc.h"
#include "system/network.h"
#include "lib/util/dlinklist.h"
#include "lib/ldb/include/ldb.h"
#include "heimdal/lib/krb5/krb5_locl.h"
#include "heimdal/lib/krb5/krb5-private.h"
#include "auth/gensec/gensec.h"
#include "auth/credentials/credentials.h"
#include "auth/credentials/credentials_krb5.h"
#include "auth/auth.h"
#include "dsdb/samdb/samdb.h"
#include "rpc_server/dcerpc_server.h"
#include "rpc_server/samr/proto.h"
#include "libcli/security/security.h"
#include "param/param.h"

/* hold information about one kdc socket */
struct kpasswd_socket {
	struct socket_context *sock;
	struct kdc_server *kdc;
	struct fd_event *fde;

	/* a queue of outgoing replies that have been deferred */
	struct kdc_reply *send_queue;
};

/* Return true if there is a valid error packet formed in the error_blob */
static bool kpasswdd_make_error_reply(struct kdc_server *kdc, 
				     TALLOC_CTX *mem_ctx, 
				     uint16_t result_code, 
				     const char *error_string, 
				     DATA_BLOB *error_blob) 
{
	char *error_string_utf8;
	ssize_t len;
	
	DEBUG(result_code ? 3 : 10, ("kpasswdd: %s\n", error_string));

	len = push_utf8_talloc(mem_ctx, lp_iconv_convenience(kdc->task->lp_ctx), &error_string_utf8, error_string);
	if (len == -1) {
		return false;
	}

	*error_blob = data_blob_talloc(mem_ctx, NULL, 2 + len + 1);
	if (!error_blob->data) {
		return false;
	}
	RSSVAL(error_blob->data, 0, result_code);
	memcpy(error_blob->data + 2, error_string_utf8, len + 1);
	return true;
}

/* Return true if there is a valid error packet formed in the error_blob */
static bool kpasswdd_make_unauth_error_reply(struct kdc_server *kdc, 
					    TALLOC_CTX *mem_ctx, 
					    uint16_t result_code, 
					    const char *error_string, 
					    DATA_BLOB *error_blob) 
{
	bool ret;
	int kret;
	DATA_BLOB error_bytes;
	krb5_data k5_error_bytes, k5_error_blob;
	ret = kpasswdd_make_error_reply(kdc, mem_ctx, result_code, error_string, 
				       &error_bytes);
	if (!ret) {
		return false;
	}
	k5_error_bytes.data = error_bytes.data;
	k5_error_bytes.length = error_bytes.length;
	kret = krb5_mk_error(kdc->smb_krb5_context->krb5_context,
			     result_code, NULL, &k5_error_bytes, 
			     NULL, NULL, NULL, NULL, &k5_error_blob);
	if (kret) {
		return false;
	}
	*error_blob = data_blob_talloc(mem_ctx, k5_error_blob.data, k5_error_blob.length);
	krb5_data_free(&k5_error_blob);
	if (!error_blob->data) {
		return false;
	}
	return true;
}

static bool kpasswd_make_pwchange_reply(struct kdc_server *kdc, 
					TALLOC_CTX *mem_ctx, 
					NTSTATUS status, 
					enum samr_RejectReason reject_reason,
					struct samr_DomInfo1 *dominfo,
					DATA_BLOB *error_blob) 
{
	if (NT_STATUS_EQUAL(status, NT_STATUS_NO_SUCH_USER)) {
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						KRB5_KPASSWD_ACCESSDENIED,
						"No such user when changing password",
						error_blob);
	}
	if (NT_STATUS_EQUAL(status, NT_STATUS_ACCESS_DENIED)) {
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						KRB5_KPASSWD_ACCESSDENIED,
						"Not permitted to change password",
						error_blob);
	}
	if (dominfo && NT_STATUS_EQUAL(status, NT_STATUS_PASSWORD_RESTRICTION)) {
		const char *reject_string;
		switch (reject_reason) {
		case SAMR_REJECT_TOO_SHORT:
			reject_string = talloc_asprintf(mem_ctx, "Password too short, password must be at least %d characters long",
							dominfo->min_password_length);
			break;
		case SAMR_REJECT_COMPLEXITY:
			reject_string = "Password does not meet complexity requirements";
			break;
		case SAMR_REJECT_IN_HISTORY:
			reject_string = "Password is already in password history";
			break;
		case SAMR_REJECT_OTHER:
		default:
			reject_string = talloc_asprintf(mem_ctx, "Password must be at least %d characters long, and cannot match any of your %d previous passwords",
							dominfo->min_password_length, dominfo->password_history_length);
			break;
		}
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						KRB5_KPASSWD_SOFTERROR,
						reject_string,
						error_blob);
	}
	if (!NT_STATUS_IS_OK(status)) {
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						 KRB5_KPASSWD_HARDERROR,
						 talloc_asprintf(mem_ctx, "failed to set password: %s", nt_errstr(status)),
						 error_blob);
		
	}
	return kpasswdd_make_error_reply(kdc, mem_ctx, KRB5_KPASSWD_SUCCESS,
					"Password changed",
					error_blob);
}

/* 
   A user password change
   
   Return true if there is a valid error packet (or sucess) formed in
   the error_blob
*/
static bool kpasswdd_change_password(struct kdc_server *kdc,
				     TALLOC_CTX *mem_ctx, 
				     struct auth_session_info *session_info,
				     const char *password,
				     DATA_BLOB *reply)
{
	NTSTATUS status;
	enum samr_RejectReason reject_reason;
	struct samr_DomInfo1 *dominfo;
	struct ldb_context *samdb;

	samdb = samdb_connect(mem_ctx, kdc->task->event_ctx, kdc->task->lp_ctx, system_session(mem_ctx, kdc->task->lp_ctx));
	if (!samdb) {
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						KRB5_KPASSWD_HARDERROR,
						"Failed to open samdb",
						reply);
	}
	
	DEBUG(3, ("Changing password of %s\\%s (%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)));

	/* User password change */
	status = samdb_set_password_sid(samdb, mem_ctx, 
					session_info->security_token->user_sid,
					password, NULL, NULL, 
					true, /* this is a user password change */
					&reject_reason,
					&dominfo);
	return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
					   status, 
					   reject_reason,
					   dominfo, 
					   reply);

}

static bool kpasswd_process_request(struct kdc_server *kdc,
				    TALLOC_CTX *mem_ctx, 
				    struct gensec_security *gensec_security,
				    uint16_t version,
				    DATA_BLOB *input, 
				    DATA_BLOB *reply)
{
	struct auth_session_info *session_info;
	if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security, 
						 &session_info))) {
		return kpasswdd_make_error_reply(kdc, mem_ctx, 
						KRB5_KPASSWD_HARDERROR,
						"gensec_session_info failed!",
						reply);
	}

	switch (version) {
	case KRB5_KPASSWD_VERS_CHANGEPW:
	{
		char *password = talloc_strndup(mem_ctx, (const char *)input->data, input->length);
		if (!password) {
			return false;
		}
		return kpasswdd_change_password(kdc, mem_ctx, session_info, 
						password, reply);
		break;
	}
	case KRB5_KPASSWD_VERS_SETPW:
	{
		NTSTATUS status;
		enum samr_RejectReason reject_reason = SAMR_REJECT_OTHER;
		struct samr_DomInfo1 *dominfo = NULL;
		struct ldb_context *samdb;
		struct ldb_message *msg;
		krb5_context context = kdc->smb_krb5_context->krb5_context;

		ChangePasswdDataMS chpw;
		char *password;

		krb5_principal principal;
		char *set_password_on_princ;
		struct ldb_dn *set_password_on_dn;

		size_t len;
		int ret;

		msg = ldb_msg_new(mem_ctx);
		if (!msg) {
			return false;
		}

		ret = decode_ChangePasswdDataMS(input->data, input->length,
						&chpw, &len);
		if (ret) {
			return kpasswdd_make_error_reply(kdc, mem_ctx, 
							KRB5_KPASSWD_MALFORMED,
							"failed to decode password change structure",
							reply);
		}
		
		password = talloc_strndup(mem_ctx, 
					  (const char *)chpw.newpasswd.data, 
					  chpw.newpasswd.length);
		if (!password) {
			free_ChangePasswdDataMS(&chpw);
			return false;
		}
		if ((chpw.targname && !chpw.targrealm) 
		    || (!chpw.targname && chpw.targrealm)) {
			return kpasswdd_make_error_reply(kdc, mem_ctx, 
							KRB5_KPASSWD_MALFORMED,
							"Realm and principal must be both present, or neither present",
							reply);
		}
		if (chpw.targname && chpw.targrealm) {
			if (_krb5_principalname2krb5_principal(kdc->smb_krb5_context->krb5_context,
							       &principal, *chpw.targname, 
							       *chpw.targrealm) != 0) {
				free_ChangePasswdDataMS(&chpw);
				return kpasswdd_make_error_reply(kdc, mem_ctx, 
								KRB5_KPASSWD_MALFORMED,
								"failed to extract principal to set",
								reply);
				
			}
		} else {
			free_ChangePasswdDataMS(&chpw);
			return kpasswdd_change_password(kdc, mem_ctx, session_info, 
							password, reply);
		}
		free_ChangePasswdDataMS(&chpw);

		if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {