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1bb5708e192a0037550d72fbcfc472c215197e03
heimdal/kdc/digest.c
Love Hörnquist Åstrand 1bb5708e19 Catch more error, add SASL DIGEST MD5. 
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@17945 ec53bebd-3082-4978-b11e-865c3cabbd6b
2006-08-28 12:38:44 +00:00

709 lines
18 KiB
C
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/*
* Copyright (c) 2006 Kungliga Tekniska Högskolan
* (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 <digest_asn1.h>
#include <hex.h>
RCSID("$Id$");
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;
char *password = NULL;
krb5_data serverNonce;
if(!config->enable_digest) {
kdc_log(context, config, 0, "Rejected digest request 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;
}
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;
hdb_entry_ex *client;
ret = krb5_ticket_get_client(context, ticket, &principal);
if (ret)
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) {
krb5_set_error_string(context,
"Client is not permitted to use digest");
ret = KRB5KDC_ERR_POLICY;
_kdc_free_ent (context, client);
goto out;
}
_kdc_free_ent (context, client);
}
/* 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;
}
/*
* 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;
}
ret = krb5_store_stringz(sp, *r.u.initReply.identifier);
if (ret) {
krb5_clear_error_string(context);
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;
}
{
Key *key;
krb5_enctype enctype;
ret = _kdc_get_preferred_key(context,
config,
server,
"digest-service",
&enctype,
&key);
if (ret)
goto out;
ret = krb5_crypto_init(context, &key->key, 0, &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");
hex_encode(buf.data, buf.length, &r.u.initReply.opaque);
if (r.u.initReply.opaque == NULL) {
krb5_clear_error_string(context);
ret = ENOMEM;
goto out;
}
break;
}
case choice_DigestReqInner_digestRequest: {
krb5_principal clientprincipal;
HDB *db;
sp = krb5_storage_emem();
if (sp == NULL) {
ret = ENOMEM;
krb5_set_error_string(context, "out of memory");
goto out;
}
krb5_store_stringz(sp, ireq.u.digestRequest.type);
krb5_store_stringz(sp, ireq.u.digestRequest.serverNonce);
if (ireq.u.digestRequest.identifier) {
ret = krb5_store_stringz(sp, *ireq.u.digestRequest.identifier);
if (ret) {
krb5_clear_error_string(context);
goto out;
}
}
if (ireq.u.digestRequest.hostname) {
ret = krb5_store_stringz(sp, *ireq.u.digestRequest.hostname);
if (ret) {
krb5_clear_error_string(context);
goto out;
}
}
buf.length = strlen(ireq.u.digestRequest.opaque);
buf.data = malloc(buf.length);
if (buf.data == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
goto out;
}
ret = hex_decode(ireq.u.digestRequest.opaque, buf.data, buf.length);
if (ret <= 0) {
krb5_set_error_string(context, "Failed to decode opaque");
ret = ENOMEM;
goto out;
}
buf.length = ret;
ret = decode_Checksum(buf.data, buf.length, &res, NULL);
free(buf.data);
if (ret) {
krb5_set_error_string(context, "Failed to decode digest Checksum");
goto out;
}
ret = krb5_storage_to_data(sp, &buf);
if (ret) {
krb5_clear_error_string(context);
goto out;
}
serverNonce.length = strlen(ireq.u.digestRequest.serverNonce);
serverNonce.data = malloc(serverNonce.length);
if (serverNonce.data == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
goto out;
}
/*
* CHAP does the checksum of the raw nonce, but do it for all
* types, since we need to check the timestamp.
*/
{
ssize_t ssize;
ssize = hex_decode(ireq.u.digestRequest.serverNonce,
serverNonce.data, serverNonce.length);
if (ssize <= 0) {
krb5_set_error_string(context, "Failed to decode serverNonce");
ret = ENOMEM;
goto out;
}
serverNonce.length = ssize;
}
{
Key *key;
krb5_enctype enctype;
ret = _kdc_get_preferred_key(context,
config,
server,
"digest-service",
&enctype,
&key);
if (ret)
goto out;
ret = krb5_crypto_init(context, &key->key, 0, &crypto);
if (ret)
goto out;
}
ret = krb5_verify_checksum(context, crypto,
KRB5_KU_DIGEST_OPAQUE,
buf.data, buf.length, &res);
krb5_crypto_destroy(context, crypto);
crypto = NULL;
if (ret)
goto out;
/* verify time */
{
unsigned char *p = serverNonce.data;
uint32_t t;
if (serverNonce.length < 4) {
krb5_set_error_string(context, "server nonce too short");
ret = EINVAL;
goto out;
}
t = p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
if (abs((kdc_time & 0xffffffff) - t) > context->max_skew) {
krb5_set_error_string(context, "time screw in server nonce ");
ret = EINVAL;
goto out;
}
}
/* get username */
ret = krb5_parse_name(context,
ireq.u.digestRequest.username,
&clientprincipal);
if (ret)
goto out;
ret = _kdc_db_fetch(context, config, clientprincipal,
HDB_F_GET_CLIENT, &db, &user);
if (ret)
goto out;
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");
}
goto out;
}
if (strcasecmp(ireq.u.digestRequest.type, "CHAP") == 0) {
MD5_CTX ctx;
char md[MD5_DIGEST_LENGTH];
char id;
if (ireq.u.digestRequest.identifier == NULL) {
krb5_set_error_string(context, "Identifier missing "
"from CHAP request");
ret = EINVAL;
goto out;
}
if (hex_decode(*ireq.u.digestRequest.identifier, &id, 1) != 1) {
krb5_set_error_string(context, "failed to decode identifier");
ret = EINVAL;
goto out;
}
MD5_Init(&ctx);
MD5_Update(&ctx, &id, 1);
MD5_Update(&ctx, password, strlen(password));
MD5_Update(&ctx, serverNonce.data, serverNonce.length);
MD5_Final(md, &ctx);
r.element = choice_DigestRepInner_response;
hex_encode(md, sizeof(md), &r.u.response.responseData);
if (r.u.response.responseData == NULL) {
krb5_clear_error_string(context);
ret = ENOMEM;
goto out;
}
} else if (strcasecmp(ireq.u.digestRequest.type, "SASL-DIGEST-MD5") == 0) {
MD5_CTX ctx;
char md[MD5_DIGEST_LENGTH];
char *A1, *A2;
if (ireq.u.digestRequest.nonceCount == NULL)
goto out;
if (ireq.u.digestRequest.clientNonce == NULL)
goto out;
if (ireq.u.digestRequest.qop == NULL)
goto out;
if (ireq.u.digestRequest.realm == NULL)
goto out;
MD5_Init(&ctx);
MD5_Update(&ctx, ireq.u.digestRequest.username,
strlen(ireq.u.digestRequest.username));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, *ireq.u.digestRequest.realm,
strlen(*ireq.u.digestRequest.realm));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, password, strlen(password));
MD5_Final(md, &ctx);
MD5_Init(&ctx);
MD5_Update(&ctx, md, sizeof(md));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, ireq.u.digestRequest.serverNonce,
strlen(ireq.u.digestRequest.serverNonce));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, *ireq.u.digestRequest.nonceCount,
strlen(*ireq.u.digestRequest.nonceCount));
if (ireq.u.digestRequest.authid) {
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, *ireq.u.digestRequest.authid,
strlen(*ireq.u.digestRequest.authid));
}
MD5_Final(md, &ctx);
hex_encode(md, sizeof(md), &A1);
if (A1 == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
goto out;
}
MD5_Init(&ctx);
MD5_Update(&ctx, "AUTHENTICATE:", sizeof("AUTHENTICATE:") - 1);
MD5_Update(&ctx, *ireq.u.digestRequest.uri,
strlen(*ireq.u.digestRequest.uri));
/* conf|int */
if (strcmp(ireq.u.digestRequest.digest, "clear") != 0) {
static char conf_zeros[] = ":00000000000000000000000000000000";
MD5_Update(&ctx, conf_zeros, sizeof(conf_zeros) - 1);
}
MD5_Final(md, &ctx);
hex_encode(md, sizeof(md), &A2);
if (A2 == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
free(A1);
goto out;
}
MD5_Init(&ctx);
MD5_Update(&ctx, A1, strlen(A2));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, ireq.u.digestRequest.serverNonce,
strlen(ireq.u.digestRequest.serverNonce));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, *ireq.u.digestRequest.nonceCount,
strlen(*ireq.u.digestRequest.nonceCount));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, *ireq.u.digestRequest.clientNonce,
strlen(*ireq.u.digestRequest.clientNonce));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, *ireq.u.digestRequest.qop,
strlen(*ireq.u.digestRequest.qop));
MD5_Update(&ctx, ":", 1);
MD5_Update(&ctx, A2, strlen(A2));
MD5_Final(md, &ctx);
r.element = choice_DigestRepInner_response;
hex_encode(md, sizeof(md), &r.u.response.responseData);
free(A1);
free(A2);
if (r.u.response.responseData == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
goto out;
}
} else {
r.element = choice_DigestRepInner_error;
asprintf(&r.u.error.reason, "unsupported digest type %s",
ireq.u.digestRequest.type);
if (r.u.error.reason == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
goto out;
}
r.u.error.code = EINVAL;
}
break;
}
default:
r.element = choice_DigestRepInner_error;
r.u.error.reason = strdup("unknown operation");
if (r.u.error.reason == NULL) {
krb5_set_error_string(context, "out of memory");
ret = ENOMEM;
goto out;
}
r.u.error.code = EINVAL;
break;
}
ASN1_MALLOC_ENCODE(DigestRepInner, buf.data, buf.length, &r, &size, ret);
if (ret) {
krb5_set_error_string(context, "Failed to encode inner digest reply");
goto out;
}
if (size != buf.length)
krb5_abortx(context, "ASN1 internal error");
krb5_auth_con_addflags(context, ac, KRB5_AUTH_CONTEXT_USE_SUBKEY, NULL);
ret = krb5_mk_rep (context, ac, &rep.apRep);
if (ret)
goto out;
{
krb5_keyblock *key;
ret = krb5_auth_con_getlocalsubkey(context, ac, &key);
if (ret)
goto out;
ret = krb5_crypto_init(context, key, 0, &crypto);
krb5_free_keyblock (context, key);
if (ret)
goto out;
}
ret = krb5_encrypt_EncryptedData(context, crypto, KRB5_KU_DIGEST_ENCRYPT,
buf.data, buf.length, 0,
&rep.innerRep);
ASN1_MALLOC_ENCODE(DigestREP, reply->data, reply->length, &rep, &size, ret);
if (ret) {
krb5_set_error_string(context, "Failed to encode digest reply");
goto out;
}
if (size != reply->length)
krb5_abortx(context, "ASN1 internal error");
out:
if (ret)
krb5_warn(context, ret, "Digest request from %s failed", from);
if (ticket)
krb5_free_ticket(context, ticket);
if (id)
krb5_kt_close(context, id);
if (crypto)
krb5_crypto_destroy(context, crypto);
if (sp)
krb5_storage_free(sp);
if (user)
_kdc_free_ent (context, user);
if (server)
_kdc_free_ent (context, server);
if (password) {
memset(password, 0, strlen(password));
free (password);
}
krb5_data_free(&buf);
krb5_data_free(&serverNonce);
free_DigestREP(&rep);
free_DigestRepInner(&r);
free_DigestReqInner(&ireq);
return ret;
}
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