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/*
* kdc/fast_util.c
*
* Copyright (C) 2009 by the Massachusetts Institute of Technology.
* All rights reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
*
*
*/
#include <k5-int.h>
#include "kdc_util.h"
#include "extern.h"
/*
* This function will find the fast and cookie padata and if fast is
* successfully processed, will throw away (and free) the outer
* request and update the pointer to point to the inner request. The
* checksummed_data points to the data that is in the
* armored_fast_request checksum; either the pa-tgs-req or the
* kdc-req-body.
*/
static krb5_error_code armor_ap_request
(struct kdc_request_state *state, krb5_fast_armor *armor)
{
krb5_error_code retval = 0;
krb5_auth_context authcontext = NULL;
krb5_ticket *ticket = NULL;
krb5_keyblock *subkey = NULL;
assert(armor->armor_type == KRB5_FAST_ARMOR_AP_REQUEST);
krb5_clear_error_message(kdc_context);
retval = krb5_auth_con_init(kdc_context, &authcontext);
if (retval == 0)
retval = krb5_auth_con_setflags(kdc_context, authcontext, 0); /*disable replay cache*/
retval = krb5_rd_req(kdc_context, &authcontext,
&armor->armor_value, NULL /*server*/,
kdc_active_realm->realm_keytab, NULL, &ticket);
if (retval !=0) {
const char * errmsg = krb5_get_error_message(kdc_context, retval);
krb5_set_error_message(kdc_context, retval,
"%s while handling ap-request armor", errmsg);
krb5_free_error_message(kdc_context, errmsg);
}
if (retval == 0) {
if (!krb5_principal_compare_any_realm(kdc_context,
tgs_server,
ticket->server)) {
krb5_set_error_message(kdc_context, KRB5KDC_ERR_SERVER_NOMATCH,
"ap-request armor for something other than the local TGS");
retval = KRB5KDC_ERR_SERVER_NOMATCH;
}
}
if (retval ==0) {
retval = krb5_auth_con_getrecvsubkey(kdc_context, authcontext, &subkey);
if (retval !=0 || subkey == NULL) {
krb5_set_error_message(kdc_context, KRB5KDC_ERR_POLICY,
"ap-request armor without subkey");
retval = KRB5KDC_ERR_POLICY;
}
}
if (retval==0)
retval = krb5_c_fx_cf2_simple(kdc_context,
subkey, "subkeyarmor",
ticket->enc_part2->session, "ticketarmor",
&state->armor_key);
if (ticket)
krb5_free_ticket(kdc_context, ticket);
if (subkey)
krb5_free_keyblock(kdc_context, subkey);
if (authcontext)
krb5_auth_con_free(kdc_context, authcontext);
return retval;
}
static krb5_error_code encrypt_fast_reply
(struct kdc_request_state *state, const krb5_fast_response *response,
krb5_data **fx_fast_reply)
{
krb5_error_code retval = 0;
krb5_enc_data encrypted_reply;
krb5_data *encoded_response = NULL;
assert(state->armor_key);
retval = encode_krb5_fast_response(response, &encoded_response);
if (retval== 0)
retval = krb5_encrypt_helper(kdc_context, state->armor_key,
KRB5_KEYUSAGE_FAST_REP,
encoded_response, &encrypted_reply);
if (encoded_response)
krb5_free_data(kdc_context, encoded_response);
encoded_response = NULL;
if (retval == 0) {
retval = encode_krb5_pa_fx_fast_reply(&encrypted_reply,
fx_fast_reply);
krb5_free_data_contents(kdc_context, &encrypted_reply.ciphertext);
}
return retval;
}
krb5_error_code kdc_find_fast
(krb5_kdc_req **requestptr, krb5_data *checksummed_data,
krb5_keyblock *tgs_subkey,
krb5_keyblock *tgs_session,
struct kdc_request_state *state)
{
krb5_error_code retval = 0;
krb5_pa_data *fast_padata, *cookie_padata;
krb5_data scratch;
krb5_fast_req * fast_req = NULL;
krb5_kdc_req *request = *requestptr;
krb5_fast_armored_req *fast_armored_req = NULL;
krb5_boolean cksum_valid;
scratch.data = NULL;
krb5_clear_error_message(kdc_context);
fast_padata = find_pa_data(request->padata,
KRB5_PADATA_FX_FAST);
if (fast_padata != NULL){
scratch.length = fast_padata->length;
scratch.data = (char *) fast_padata->contents;
retval = decode_krb5_pa_fx_fast_request(&scratch, &fast_armored_req);
if (retval == 0 &&fast_armored_req->armor) {
switch (fast_armored_req->armor->armor_type) {
case KRB5_FAST_ARMOR_AP_REQUEST:
retval = armor_ap_request(state, fast_armored_req->armor);
break;
default:
krb5_set_error_message(kdc_context, KRB5KDC_ERR_PREAUTH_FAILED,
"Unknow FAST armor type %d",
fast_armored_req->armor->armor_type);
retval = KRB5KDC_ERR_PREAUTH_FAILED;
}
}
if (retval == 0 && !state->armor_key) {
if (tgs_subkey)
retval = krb5_c_fx_cf2_simple(kdc_context,
tgs_subkey, "subkeyarmor",
tgs_session, "ticketarmor",
&state->armor_key);
else {
krb5_set_error_message(kdc_context, KRB5KDC_ERR_PREAUTH_FAILED,
"No armor key but FAST armored request present");
retval = KRB5KDC_ERR_PREAUTH_FAILED;
}
}
if (retval == 0) {
krb5_data plaintext;
plaintext.length = fast_armored_req->enc_part.ciphertext.length;
plaintext.data = malloc(plaintext.length);
if (plaintext.data == NULL)
retval = ENOMEM;
retval = krb5_c_decrypt(kdc_context,
state->armor_key,
KRB5_KEYUSAGE_FAST_ENC, NULL,
&fast_armored_req->enc_part,
&plaintext);
if (retval == 0)
retval = decode_krb5_fast_req(&plaintext, &fast_req);
if (plaintext.data)
free(plaintext.data);
}
if (retval == 0)
retval = krb5_c_verify_checksum(kdc_context, state->armor_key,
KRB5_KEYUSAGE_FAST_REQ_CHKSUM,
checksummed_data, &fast_armored_req->req_checksum,
&cksum_valid);
if (retval == 0 && !cksum_valid) {
retval = KRB5KRB_AP_ERR_MODIFIED;
krb5_set_error_message(kdc_context, KRB5KRB_AP_ERR_MODIFIED,
"FAST req_checksum invalid; request modified");
}
if (retval == 0) {
if ((fast_req->fast_options & UNSUPPORTED_CRITICAL_FAST_OPTIONS) !=0)
retval = KRB5KDC_ERR_UNKNOWN_CRITICAL_FAST_OPTION;
}
if (retval == 0)
cookie_padata = find_pa_data(fast_req->req_body->padata, KRB5_PADATA_FX_COOKIE);
if (retval == 0) {
state->fast_options = fast_req->fast_options;
if (request->kdc_state == state)
request->kdc_state = NULL;
krb5_free_kdc_req( kdc_context, request);
*requestptr = fast_req->req_body;
fast_req->req_body = NULL;
}
}
else cookie_padata = find_pa_data(request->padata, KRB5_PADATA_FX_COOKIE);
if (retval == 0 && cookie_padata != NULL) {
krb5_pa_data *new_padata = malloc(sizeof (krb5_pa_data));
if (new_padata != NULL) {
retval = ENOMEM;
} else {
new_padata->pa_type = KRB5_PADATA_FX_COOKIE;
new_padata->length = cookie_padata->length;
new_padata->contents = malloc(new_padata->length);
if (new_padata->contents == NULL) {
retval = ENOMEM;
free(new_padata);
} else {
memcpy(new_padata->contents, cookie_padata->contents, new_padata->length);
state->cookie = new_padata;
}
}
}
if (fast_req)
krb5_free_fast_req( kdc_context, fast_req);
if (fast_armored_req)
krb5_free_fast_armored_req(kdc_context, fast_armored_req);
return retval;
}
krb5_error_code kdc_make_rstate(struct kdc_request_state **out)
{
struct kdc_request_state *state = malloc( sizeof(struct kdc_request_state));
if (state == NULL)
return ENOMEM;
memset( state, 0, sizeof(struct kdc_request_state));
*out = state;
return 0;
}
void kdc_free_rstate
(struct kdc_request_state *s)
{
if (s == NULL)
return;
if (s->armor_key)
krb5_free_keyblock(kdc_context, s->armor_key);
if (s->reply_key)
krb5_free_keyblock(kdc_context, s->reply_key);
if (s->cookie) {
free(s->cookie->contents);
free(s->cookie);
}
free(s);
}
krb5_error_code kdc_fast_response_handle_padata
(struct kdc_request_state *state,
krb5_kdc_req *request,
krb5_kdc_rep *rep)
{
krb5_error_code retval = 0;
krb5_fast_finished finish;
krb5_fast_response fast_response;
krb5_data *encoded_ticket = NULL;
krb5_data *encrypted_reply = NULL;
krb5_pa_data *pa = NULL, **pa_array = NULL;
krb5_cksumtype cksumtype = CKSUMTYPE_RSA_MD5;
krb5_pa_data *empty_padata[] = {NULL};
if (!state->armor_key)
return 0;
memset(&finish, 0, sizeof(finish));
fast_response.padata = rep->padata;
if (fast_response.padata == NULL)
fast_response.padata = &empty_padata[0];
fast_response.rep_key = state->reply_key;
fast_response.nonce = request->nonce;
fast_response.finished = &finish;
finish.client = rep->client;
pa_array = calloc(3, sizeof(*pa_array));
if (pa_array == NULL)
retval = ENOMEM;
pa = calloc(1, sizeof(krb5_pa_data));
if (retval == 0 && pa == NULL)
retval = ENOMEM;
if (retval == 0)
retval = krb5_us_timeofday(kdc_context, &finish.timestamp, &finish.usec);
if (retval == 0)
retval = encode_krb5_ticket(rep->ticket, &encoded_ticket);
if (retval == 0)
retval = krb5int_c_mandatory_cksumtype(kdc_context, state->armor_key->enctype, &cksumtype);
if (retval == 0)
retval = krb5_c_make_checksum(kdc_context, cksumtype,
state->armor_key, KRB5_KEYUSAGE_FAST_FINISHED,
encoded_ticket, &finish.ticket_checksum);
if (retval == 0)
retval = encrypt_fast_reply(state, &fast_response, &encrypted_reply);
if (retval == 0) {
pa[0].pa_type = KRB5_PADATA_FX_FAST;
pa[0].length = encrypted_reply->length;
pa[0].contents = (unsigned char *) encrypted_reply->data;
pa_array[0] = &pa[0];
rep->padata = pa_array;
pa_array = NULL;
free(encrypted_reply);
encrypted_reply = NULL;
pa = NULL;
}
if (pa)
free(pa);
if (pa_array)
free(pa_array);
if (encrypted_reply)
krb5_free_data(kdc_context, encrypted_reply);
if (encoded_ticket)
krb5_free_data(kdc_context, encoded_ticket);
if (finish.ticket_checksum.contents)
krb5_free_checksum_contents(kdc_context, &finish.ticket_checksum);
return retval;
}
/*
* We assume the caller is responsible for passing us an in_padata
* sufficient to include in a FAST error. In the FAST case we will
* throw away the e_data in the error (if any); in the non-FAST case
* we will not use the in_padata.
*/
krb5_error_code kdc_fast_handle_error
(krb5_context context, struct kdc_request_state *state,
krb5_kdc_req *request,
krb5_pa_data **in_padata, krb5_error *err)
{
krb5_error_code retval = 0;
krb5_fast_response resp;
krb5_error fx_error;
krb5_data *encoded_fx_error = NULL, *encrypted_reply = NULL;
krb5_pa_data pa[1];
krb5_pa_data *outer_pa[3], *cookie = NULL;
krb5_pa_data **inner_pa = NULL;
size_t size = 0;
krb5_data *encoded_e_data = NULL;
memset(outer_pa, 0, sizeof(outer_pa));
if (!state->armor_key)
return 0;
fx_error = *err;
fx_error.e_data.data = NULL;
fx_error.e_data.length = 0;
for (size = 0; in_padata&&in_padata[size]; size++);
size +=3;
inner_pa = calloc(size, sizeof(krb5_pa_data *));
if (inner_pa == NULL)
retval = ENOMEM;
if (retval == 0)
for (size=0; in_padata&&in_padata[size]; size++)
inner_pa[size] = in_padata[size];
if (retval == 0)
retval = encode_krb5_error(&fx_error, &encoded_fx_error);
if (retval == 0) {
pa[0].pa_type = KRB5_PADATA_FX_ERROR;
pa[0].length = encoded_fx_error->length;
pa[0].contents = (unsigned char *) encoded_fx_error->data;
inner_pa[size++] = &pa[0];
if (find_pa_data(inner_pa, KRB5_PADATA_FX_COOKIE) == NULL)
retval = kdc_preauth_get_cookie(state, &cookie);
}
if (cookie != NULL)
inner_pa[size++] = cookie;
if (retval == 0) {
resp.padata = inner_pa;
resp.nonce = request->nonce;
resp.rep_key = NULL;
resp.finished = NULL;
}
if (retval == 0)
retval = encrypt_fast_reply(state, &resp, &encrypted_reply);
if (inner_pa)
free(inner_pa); /*contained storage from caller and our stack*/
if (cookie) {
free(cookie->contents);
free(cookie);
cookie = NULL;
}
if (retval == 0) {
pa[0].pa_type = KRB5_PADATA_FX_FAST;
pa[0].length = encrypted_reply->length;
pa[0].contents = (unsigned char *) encrypted_reply->data;
outer_pa[0] = &pa[0];
}
retval = encode_krb5_padata_sequence(outer_pa, &encoded_e_data);
if (retval == 0) {
/*process_as holds onto a pointer to the original e_data and frees it*/
err->e_data = *encoded_e_data;
free(encoded_e_data); /*contents belong to err*/
encoded_e_data = NULL;
}
if (encoded_e_data)
krb5_free_data(kdc_context, encoded_e_data);
if (encrypted_reply)
krb5_free_data(kdc_context, encrypted_reply);
if (encoded_fx_error)
krb5_free_data(kdc_context, encoded_fx_error);
return retval;
}
krb5_error_code kdc_preauth_get_cookie(struct kdc_request_state *state,
krb5_pa_data **cookie)
{
char *contents;
krb5_pa_data *pa = NULL;
/* In our current implementation, the only purpose served by
* returning a cookie is to indicate that a conversation should
* continue on error. Thus, the cookie can have a constant
* string. If cookies are used for real, versioning so that KDCs
* can be upgraded, keying, expiration and many other issues need
* to be considered.
*/
contents = strdup("MIT");
if (contents == NULL)
return ENOMEM;
pa = calloc(1, sizeof(krb5_pa_data));
if (pa == NULL) {
free(contents);
return ENOMEM;
}
pa->pa_type = KRB5_PADATA_FX_COOKIE;
pa->length = strlen(contents);
pa->contents = (unsigned char *) contents;
*cookie = pa;
return 0;
}
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