digest.c

samba最新软件

/*
 * Copyright (c) 2006 - 2007 Kungliga Tekniska H鰃skolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#include "kdc_locl.h"
#include <hex.h>

RCSID("$Id: digest.c 22374 2007-12-28 18:36:52Z lha $");

#define MS_CHAP_V2	0x20
#define CHAP_MD5	0x10
#define DIGEST_MD5	0x08
#define NTLM_V2		0x04
#define NTLM_V1_SESSION	0x02
#define NTLM_V1		0x01

const struct units _kdc_digestunits[] = {
	{"ms-chap-v2",		1U << 5},
	{"chap-md5",		1U << 4},
	{"digest-md5",		1U << 3},
	{"ntlm-v2",		1U << 2},
	{"ntlm-v1-session",	1U << 1},
	{"ntlm-v1",		1U << 0},
	{NULL,	0}
};


static krb5_error_code
get_digest_key(krb5_context context,
	       krb5_kdc_configuration *config,
	       hdb_entry_ex *server,
	       krb5_crypto *crypto)
{
    krb5_error_code ret;
    krb5_enctype enctype;
    Key *key;
    
    ret = _kdc_get_preferred_key(context,
				 config,
				 server,
				 "digest-service",
				 &enctype,
				 &key);
    if (ret)
	return ret;
    return krb5_crypto_init(context, &key->key, 0, crypto);
}

/*
 *
 */

static char *
get_ntlm_targetname(krb5_context context,
		    hdb_entry_ex *client)
{
    char *targetname, *p;

    targetname = strdup(krb5_principal_get_realm(context,
						 client->entry.principal));
    if (targetname == NULL)
	return NULL;

    p = strchr(targetname, '.');
    if (p)
	*p = '\0';

    strupr(targetname);
    return targetname;
}

static krb5_error_code
fill_targetinfo(krb5_context context,
		char *targetname,
		hdb_entry_ex *client,
		krb5_data *data)
{
    struct ntlm_targetinfo ti;
    krb5_error_code ret;
    struct ntlm_buf d;
    krb5_principal p;
    const char *str;

    memset(&ti, 0, sizeof(ti));

    ti.domainname = targetname;
    p = client->entry.principal;
    str = krb5_principal_get_comp_string(context, p, 0);
    if (str != NULL && 
	(strcmp("host", str) == 0 || 
	 strcmp("ftp", str) == 0 ||
	 strcmp("imap", str) == 0 ||
	 strcmp("pop", str) == 0 ||
	 strcmp("smtp", str)))
    {
	str = krb5_principal_get_comp_string(context, p, 1);
	ti.dnsservername = rk_UNCONST(str);
    }
    
    ret = heim_ntlm_encode_targetinfo(&ti, 1, &d);
    if (ret)
	return ret;

    data->data = d.data;
    data->length = d.length;

    return 0;
}


static const unsigned char ms_chap_v2_magic1[39] = {
    0x4D, 0x61, 0x67, 0x69, 0x63, 0x20, 0x73, 0x65, 0x72, 0x76,
    0x65, 0x72, 0x20, 0x74, 0x6F, 0x20, 0x63, 0x6C, 0x69, 0x65,
    0x6E, 0x74, 0x20, 0x73, 0x69, 0x67, 0x6E, 0x69, 0x6E, 0x67,
    0x20, 0x63, 0x6F, 0x6E, 0x73, 0x74, 0x61, 0x6E, 0x74
};
static const unsigned char ms_chap_v2_magic2[41] = {
    0x50, 0x61, 0x64, 0x20, 0x74, 0x6F, 0x20, 0x6D, 0x61, 0x6B,
    0x65, 0x20, 0x69, 0x74, 0x20, 0x64, 0x6F, 0x20, 0x6D, 0x6F,
    0x72, 0x65, 0x20, 0x74, 0x68, 0x61, 0x6E, 0x20, 0x6F, 0x6E,
    0x65, 0x20, 0x69, 0x74, 0x65, 0x72, 0x61, 0x74, 0x69, 0x6F,
    0x6E
};
static const unsigned char ms_rfc3079_magic1[27] = {
    0x54, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74,
    0x68, 0x65, 0x20, 0x4d, 0x50, 0x50, 0x45, 0x20, 0x4d,
    0x61, 0x73, 0x74, 0x65, 0x72, 0x20, 0x4b, 0x65, 0x79
};

/*
 *
 */

static krb5_error_code
get_password_entry(krb5_context context,
		   krb5_kdc_configuration *config,
		   const char *username,
		   char **password)
{
    krb5_principal clientprincipal;
    krb5_error_code ret;
    hdb_entry_ex *user;
    HDB *db;

    /* get username */
    ret = krb5_parse_name(context, username, &clientprincipal);
    if (ret)
	return ret;

    ret = _kdc_db_fetch(context, config, clientprincipal,
			HDB_F_GET_CLIENT, &db, &user);
    krb5_free_principal(context, clientprincipal);
    if (ret)
	return ret;

    ret = hdb_entry_get_password(context, db, &user->entry, password);
    if (ret || password == NULL) {
	if (ret == 0) {
	    ret = EINVAL;
	    krb5_set_error_string(context, "password missing");
	}
	memset(user, 0, sizeof(*user));
    }
    _kdc_free_ent (context, user);
    return ret;
}

/*
 *
 */

krb5_error_code
_kdc_do_digest(krb5_context context, 
	       krb5_kdc_configuration *config,
	       const DigestREQ *req, krb5_data *reply,
	       const char *from, struct sockaddr *addr)
{
    krb5_error_code ret = 0;
    krb5_ticket *ticket = NULL;
    krb5_auth_context ac = NULL;
    krb5_keytab id = NULL;
    krb5_crypto crypto = NULL;
    DigestReqInner ireq;
    DigestRepInner r;
    DigestREP rep;
    krb5_flags ap_req_options;
    krb5_data buf;
    size_t size;
    krb5_storage *sp = NULL;
    Checksum res;
    hdb_entry_ex *server = NULL, *user = NULL;
    hdb_entry_ex *client = NULL;
    char *client_name = NULL, *password = NULL;
    krb5_data serverNonce;

    if(!config->enable_digest) {
	kdc_log(context, config, 0, 
		"Rejected digest request (disabled) from %s", from);
	return KRB5KDC_ERR_POLICY;
    }

    krb5_data_zero(&buf);
    krb5_data_zero(reply);
    krb5_data_zero(&serverNonce);
    memset(&ireq, 0, sizeof(ireq));
    memset(&r, 0, sizeof(r));
    memset(&rep, 0, sizeof(rep));

    kdc_log(context, config, 0, "Digest request from %s", from);

    ret = krb5_kt_resolve(context, "HDB:", &id);
    if (ret) {
	kdc_log(context, config, 0, "Can't open database for digest");
	goto out;
    }

    ret = krb5_rd_req(context, 
		      &ac,
		      &req->apReq,
		      NULL,
		      id,
		      &ap_req_options,
		      &ticket);
    if (ret)
	goto out;

    /* check the server principal in the ticket matches digest/R@R */
    {
	krb5_principal principal = NULL;
	const char *p, *r;

	ret = krb5_ticket_get_server(context, ticket, &principal);
	if (ret)
	    goto out;

	ret = EINVAL;
	krb5_set_error_string(context, "Wrong digest server principal used");
	p = krb5_principal_get_comp_string(context, principal, 0);
	if (p == NULL) {
	    krb5_free_principal(context, principal);
	    goto out;
	}
	if (strcmp(p, KRB5_DIGEST_NAME) != 0) {
	    krb5_free_principal(context, principal);
	    goto out;
	}

	p = krb5_principal_get_comp_string(context, principal, 1);
	if (p == NULL) {
	    krb5_free_principal(context, principal);
	    goto out;
	}
	r = krb5_principal_get_realm(context, principal);
	if (r == NULL) {
	    krb5_free_principal(context, principal);
	    goto out;
	}
	if (strcmp(p, r) != 0) {
	    krb5_free_principal(context, principal);
	    goto out;
	}
	krb5_clear_error_string(context);

	ret = _kdc_db_fetch(context, config, principal,
			    HDB_F_GET_SERVER, NULL, &server);
	if (ret)
	    goto out;

	krb5_free_principal(context, principal);
    }

    /* check the client is allowed to do digest auth */
    {
	krb5_principal principal = NULL;

	ret = krb5_ticket_get_client(context, ticket, &principal);
	if (ret)
	    goto out;

	ret = krb5_unparse_name(context, principal, &client_name);
	if (ret) {
	    krb5_free_principal(context, principal);
	    goto out;
	}

	ret = _kdc_db_fetch(context, config, principal,
			    HDB_F_GET_CLIENT, NULL, &client);
	krb5_free_principal(context, principal);
	if (ret)
	    goto out;

	if (client->entry.flags.allow_digest == 0) {
	    kdc_log(context, config, 0, 
		    "Client %s tried to use digest "
		    "but is not allowed to", 
		    client_name);
	    krb5_set_error_string(context, 
				  "Client is not permitted to use digest");
	    ret = KRB5KDC_ERR_POLICY;
	    goto out;
	}
    }

    /* unpack request */
    {
	krb5_keyblock *key;

	ret = krb5_auth_con_getremotesubkey(context, ac, &key);
	if (ret)
	    goto out;
	if (key == NULL) {
	    krb5_set_error_string(context, "digest: remote subkey not found");
	    ret = EINVAL;
	    goto out;
	}

	ret = krb5_crypto_init(context, key, 0, &crypto);
	krb5_free_keyblock (context, key);
	if (ret)
	    goto out;
    }

    ret = krb5_decrypt_EncryptedData(context, crypto, KRB5_KU_DIGEST_ENCRYPT,
				     &req->innerReq, &buf);
    krb5_crypto_destroy(context, crypto);
    crypto = NULL;
    if (ret)
	goto out;
	   
    ret = decode_DigestReqInner(buf.data, buf.length, &ireq, NULL);
    krb5_data_free(&buf);
    if (ret) {
	krb5_set_error_string(context, "Failed to decode digest inner request");
	goto out;
    }

    kdc_log(context, config, 0, "Valid digest request from %s (%s)", 
	    client_name, from);

    /*
     * Process the inner request
     */

    switch (ireq.element) {
    case choice_DigestReqInner_init: {
	unsigned char server_nonce[16], identifier;

	RAND_pseudo_bytes(&identifier, sizeof(identifier));
	RAND_pseudo_bytes(server_nonce, sizeof(server_nonce));

	server_nonce[0] = kdc_time & 0xff;
	server_nonce[1] = (kdc_time >> 8) & 0xff;
	server_nonce[2] = (kdc_time >> 16) & 0xff;
	server_nonce[3] = (kdc_time >> 24) & 0xff;

	r.element = choice_DigestRepInner_initReply;

	hex_encode(server_nonce, sizeof(server_nonce), &r.u.initReply.nonce);
	if (r.u.initReply.nonce == NULL) {
	    krb5_set_error_string(context, "Failed to decode server nonce");
	    ret = ENOMEM;
	    goto out;
	}

	sp = krb5_storage_emem();
	if (sp == NULL) {
	    ret = ENOMEM;
	    krb5_set_error_string(context, "out of memory");
	    goto out;
	}
	ret = krb5_store_stringz(sp, ireq.u.init.type);
	if (ret) {
	    krb5_clear_error_string(context);
	    goto out;
	}

	if (ireq.u.init.channel) {
	    char *s;

	    asprintf(&s, "%s-%s:%s", r.u.initReply.nonce,
		     ireq.u.init.channel->cb_type,
		     ireq.u.init.channel->cb_binding);
	    if (s == NULL) {
		krb5_set_error_string(context, "Failed to allocate "
				      "channel binding");
		ret = ENOMEM;
		goto out;
	    }
	    free(r.u.initReply.nonce);
	    r.u.initReply.nonce = s;
	}
	
	ret = krb5_store_stringz(sp, r.u.initReply.nonce);
	if (ret) {
	    krb5_clear_error_string(context);
	    goto out;
	}

	if (strcasecmp(ireq.u.init.type, "CHAP") == 0) {
	    r.u.initReply.identifier = 
		malloc(sizeof(*r.u.initReply.identifier));
	    if (r.u.initReply.identifier == NULL) {
		krb5_set_error_string(context, "out of memory");
		ret = ENOMEM;
		goto out;
	    }

	    asprintf(r.u.initReply.identifier, "%02X", identifier & 0xff);
	    if (*r.u.initReply.identifier == NULL) {
		krb5_set_error_string(context, "out of memory");
		ret = ENOMEM;
		goto out;
	    }

	} else
	    r.u.initReply.identifier = NULL;

	if (ireq.u.init.hostname) {
	    ret = krb5_store_stringz(sp, *ireq.u.init.hostname);
	    if (ret) {
		krb5_clear_error_string(context);
		goto out;
	    }
	}

	ret = krb5_storage_to_data(sp, &buf);
	if (ret) {
	    krb5_clear_error_string(context);
	    goto out;
	}

	ret = get_digest_key(context, config, server, &crypto);
	if (ret)
	    goto out;

	ret = krb5_create_checksum(context,
				   crypto,
				   KRB5_KU_DIGEST_OPAQUE,
				   0,
				   buf.data,
				   buf.length,
				   &res);
	krb5_crypto_destroy(context, crypto);
	crypto = NULL;
	krb5_data_free(&buf);
	if (ret)
	    goto out;
	
	ASN1_MALLOC_ENCODE(Checksum, buf.data, buf.length, &res, &size, ret);
	free_Checksum(&res);
	if (ret) {
	    krb5_set_error_string(context, "Failed to encode "
				  "checksum in digest request");
	    goto out;
	}
	if (size != buf.length)
	    krb5_abortx(context, "ASN1 internal error");