krb5_setpw.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   Unix SMB/CIFS implementation.
   krb5 set password implementation
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Remus Koos 2001 ([e-mail])
   
   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"

#ifdef HAVE_KRB5

#define DEFAULT_KPASSWD_PORT	464
#define KRB5_KPASSWD_VERS_CHANGEPW		1
#define KRB5_KPASSWD_VERS_SETPW			0xff80
#define KRB5_KPASSWD_VERS_SETPW_ALT		2
#define KRB5_KPASSWD_ACCESSDENIED		5
#define KRB5_KPASSWD_BAD_VERSION		6
#define KRB5_KPASSWD_INITIAL_FLAG_NEEDED	7

/* Those are defined by kerberos-set-passwd-02.txt and are probably 
 * not supported by M$ implementation */
#define KRB5_KPASSWD_POLICY_REJECT		8
#define KRB5_KPASSWD_BAD_PRINCIPAL		9
#define KRB5_KPASSWD_ETYPE_NOSUPP		10

/* This implements kerberos password change protocol as specified in 
 * kerb-chg-password-02.txt and kerberos-set-passwd-02.txt
 * as well as microsoft version of the protocol 
 * as specified in kerberos-set-passwd-00.txt
 */
static DATA_BLOB encode_krb5_setpw(const char *principal, const char *password)
{
        char* princ_part1 = NULL;
	char* princ_part2 = NULL;
	char* realm = NULL;
	char* c;
	char* princ;

	ASN1_DATA req;
	DATA_BLOB ret;


	princ = SMB_STRDUP(principal);

	if ((c = strchr_m(princ, '/')) == NULL) {
	    c = princ; 
	} else {
	    *c = '\0';
	    c++;
	    princ_part1 = princ;
	}

	princ_part2 = c;

	if ((c = strchr_m(c, '@')) != NULL) {
	    *c = '\0';
	    c++;
	    realm = c;
	}

	memset(&req, 0, sizeof(req));
	
	asn1_push_tag(&req, ASN1_SEQUENCE(0));
	asn1_push_tag(&req, ASN1_CONTEXT(0));
	asn1_write_OctetString(&req, password, strlen(password));
	asn1_pop_tag(&req);

	asn1_push_tag(&req, ASN1_CONTEXT(1));
	asn1_push_tag(&req, ASN1_SEQUENCE(0));

	asn1_push_tag(&req, ASN1_CONTEXT(0));
	asn1_write_Integer(&req, 1);
	asn1_pop_tag(&req);

	asn1_push_tag(&req, ASN1_CONTEXT(1));
	asn1_push_tag(&req, ASN1_SEQUENCE(0));

	if (princ_part1) 
	    asn1_write_GeneralString(&req, princ_part1);
	
	asn1_write_GeneralString(&req, princ_part2);
	asn1_pop_tag(&req);
	asn1_pop_tag(&req);
	asn1_pop_tag(&req);
	asn1_pop_tag(&req);

	asn1_push_tag(&req, ASN1_CONTEXT(2));
	asn1_write_GeneralString(&req, realm);
	asn1_pop_tag(&req);
	asn1_pop_tag(&req);

	ret = data_blob(req.data, req.length);
	asn1_free(&req);

	free(princ);

	return ret;
}	

static krb5_error_code build_kpasswd_request(uint16 pversion,
					   krb5_context context,
					   krb5_auth_context auth_context,
					   krb5_data *ap_req,
					   const char *princ,
					   const char *passwd,
					   krb5_data *packet)
{
	krb5_error_code ret;
	krb5_data cipherpw;
	krb5_data encoded_setpw;
	krb5_replay_data replay;
	char *p;
	DATA_BLOB setpw;

	ret = krb5_auth_con_setflags(context,
				     auth_context,KRB5_AUTH_CONTEXT_DO_SEQUENCE);
	if (ret) {
		DEBUG(1,("krb5_auth_con_setflags failed (%s)\n",
			 error_message(ret)));
		return ret;
	}

	/* handle protocol differences in chpw and setpw */
	if (pversion  == KRB5_KPASSWD_VERS_CHANGEPW)
		setpw = data_blob(passwd, strlen(passwd));
	else if (pversion == KRB5_KPASSWD_VERS_SETPW ||
		 pversion == KRB5_KPASSWD_VERS_SETPW_ALT)
		setpw = encode_krb5_setpw(princ, passwd);
	else
		return EINVAL;

	encoded_setpw.data = (char *)setpw.data;
	encoded_setpw.length = setpw.length;

	ret = krb5_mk_priv(context, auth_context,
			   &encoded_setpw, &cipherpw, &replay);
	
	data_blob_free(&setpw); 	/*from 'encode_krb5_setpw(...)' */
	
	if (ret) {
		DEBUG(1,("krb5_mk_priv failed (%s)\n", error_message(ret)));
		return ret;
	}

	packet->data = (char *)SMB_MALLOC(ap_req->length + cipherpw.length + 6);
	if (!packet->data)
		return -1;

	/* see the RFC for details */
	p = ((char *)packet->data) + 2;
	RSSVAL(p, 0, pversion);
	p += 2;
	RSSVAL(p, 0, ap_req->length);
	p += 2;
	memcpy(p, ap_req->data, ap_req->length);
	p += ap_req->length;
	memcpy(p, cipherpw.data, cipherpw.length);
	p += cipherpw.length;
	packet->length = PTR_DIFF(p,packet->data);
	RSSVAL(packet->data, 0, packet->length);
	
	free(cipherpw.data);    /* from 'krb5_mk_priv(...)' */

	return 0;
}

static const struct kpasswd_errors {
	int result_code;
	const char *error_string;
} kpasswd_errors[] = {
	{KRB5_KPASSWD_MALFORMED, "Malformed request error"},
	{KRB5_KPASSWD_HARDERROR, "Server error"},
	{KRB5_KPASSWD_AUTHERROR, "Authentication error"},
	{KRB5_KPASSWD_SOFTERROR, "Password change rejected"},
	{KRB5_KPASSWD_ACCESSDENIED, "Client does not have proper authorization"},
	{KRB5_KPASSWD_BAD_VERSION, "Protocol version not supported"},
	{KRB5_KPASSWD_INITIAL_FLAG_NEEDED, "Authorization ticket must have initial flag set"},
	{KRB5_KPASSWD_POLICY_REJECT, "Password rejected due to policy requirements"},
	{KRB5_KPASSWD_BAD_PRINCIPAL, "Target principal does not exist"},
	{KRB5_KPASSWD_ETYPE_NOSUPP, "Unsupported encryption type"},
	{0, NULL}
};

static krb5_error_code setpw_result_code_string(krb5_context context,
						int result_code,
						const char **code_string)
{
        unsigned int idx = 0;

	while (kpasswd_errors[idx].error_string != NULL) {
		if (kpasswd_errors[idx].result_code == 
                    result_code) {
			*code_string = kpasswd_errors[idx].error_string;
			return 0;
		}
		idx++;
	}
	*code_string = "Password change failed";
        return (0);
}

static krb5_error_code parse_setpw_reply(krb5_context context, 
					 krb5_auth_context auth_context,
					 krb5_data *packet)
{
	krb5_data ap_rep;
	char *p;
	int vnum, ret, res_code;
	krb5_data cipherresult;
	krb5_data clearresult;
	krb5_ap_rep_enc_part *ap_rep_enc;
	krb5_replay_data replay;
	
	if (packet->length < 4) {
		return KRB5KRB_AP_ERR_MODIFIED;
	}
	
	p = packet->data;
	
	if (((char *)packet->data)[0] == 0x7e || ((char *)packet->data)[0] == 0x5e) {
		/* it's an error packet. We should parse it ... */
		DEBUG(1,("Got error packet 0x%x from kpasswd server\n",
			 ((char *)packet->data)[0]));
		return KRB5KRB_AP_ERR_MODIFIED;
	}
	
	if (RSVAL(p, 0) != packet->length) {
		DEBUG(1,("Bad packet length (%d/%d) from kpasswd server\n",
			 RSVAL(p, 0), packet->length));
		return KRB5KRB_AP_ERR_MODIFIED;
	}

	p += 2;

	vnum = RSVAL(p, 0); p += 2;

	/* FIXME: According to standard there is only one type of reply */	
	if (vnum != KRB5_KPASSWD_VERS_SETPW && 
	    vnum != KRB5_KPASSWD_VERS_SETPW_ALT && 
	    vnum != KRB5_KPASSWD_VERS_CHANGEPW) {
		DEBUG(1,("Bad vnum (%d) from kpasswd server\n", vnum));
		return KRB5KDC_ERR_BAD_PVNO;
	}
	
	ap_rep.length = RSVAL(p, 0); p += 2;
	
	if (p + ap_rep.length >= (char *)packet->data + packet->length) {
		DEBUG(1,("ptr beyond end of packet from kpasswd server\n"));
		return KRB5KRB_AP_ERR_MODIFIED;
	}
	
	if (ap_rep.length == 0) {
		DEBUG(1,("got unencrypted setpw result?!\n"));
		return KRB5KRB_AP_ERR_MODIFIED;
	}

	/* verify ap_rep */
	ap_rep.data = p;
	p += ap_rep.length;
	
	ret = krb5_rd_rep(context, auth_context, &ap_rep, &ap_rep_enc);
	if (ret) {
		DEBUG(1,("failed to rd setpw reply (%s)\n", error_message(ret)));
		return KRB5KRB_AP_ERR_MODIFIED;
	}
	
	krb5_free_ap_rep_enc_part(context, ap_rep_enc);
	
	cipherresult.data = p;
	cipherresult.length = ((char *)packet->data + packet->length) - p;
		
	ret = krb5_rd_priv(context, auth_context, &cipherresult, &clearresult,
			   &replay);
	if (ret) {
		DEBUG(1,("failed to decrypt setpw reply (%s)\n", error_message(ret)));
		return KRB5KRB_AP_ERR_MODIFIED;
	}

	if (clearresult.length < 2) {
	        free(clearresult.data);
		ret = KRB5KRB_AP_ERR_MODIFIED;
		return KRB5KRB_AP_ERR_MODIFIED;
	}
	
	p = clearresult.data;
	
	res_code = RSVAL(p, 0);
	
	free(clearresult.data);

	if ((res_code < KRB5_KPASSWD_SUCCESS) || 
	    (res_code > KRB5_KPASSWD_ETYPE_NOSUPP)) {
		return KRB5KRB_AP_ERR_MODIFIED;
	}

	if(res_code == KRB5_KPASSWD_SUCCESS)
			return 0;
	else {
		const char *errstr;
		setpw_result_code_string(context, res_code, &errstr);
		DEBUG(1, ("Error changing password: %s\n", errstr));

		switch(res_code) {
			case KRB5_KPASSWD_ACCESSDENIED:
				return KRB5KDC_ERR_BADOPTION;
			case KRB5_KPASSWD_INITIAL_FLAG_NEEDED:
				return KRB5KDC_ERR_BADOPTION;
				/* return KV5M_ALT_METHOD; MIT-only define */
			case KRB5_KPASSWD_ETYPE_NOSUPP:
				return KRB5KDC_ERR_ETYPE_NOSUPP;
			case KRB5_KPASSWD_BAD_PRINCIPAL:
				return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN;
			case KRB5_KPASSWD_POLICY_REJECT:
				return KRB5KDC_ERR_POLICY;
			default:
				return KRB5KRB_ERR_GENERIC;
		}
	}
}

static ADS_STATUS do_krb5_kpasswd_request(krb5_context context,
					  const char *kdc_host,
					  uint16 pversion,
					  krb5_creds *credsp,
					  const char *princ,
					  const char *newpw)
{
	krb5_auth_context auth_context = NULL;
	krb5_data ap_req, chpw_req, chpw_rep;
	int ret, sock;
	socklen_t addr_len;
	struct sockaddr remote_addr, local_addr;
	krb5_address local_kaddr, remote_kaddr;

	ret = krb5_mk_req_extended(context, &auth_context, AP_OPTS_USE_SUBKEY,
				   NULL, credsp, &ap_req);
	if (ret) {
		DEBUG(1,("krb5_mk_req_extended failed (%s)\n", error_message(ret)));
		return ADS_ERROR_KRB5(ret);
	}
	
	sock = open_udp_socket(kdc_host, DEFAULT_KPASSWD_PORT);
	if (sock == -1) {