static void
ec_verify(krb5_context context, krb5_data *req_pkt, krb5_kdc_req *request,
krb5_enc_tkt_part *enc_tkt_reply, krb5_pa_data *data,
krb5_kdcpreauth_callbacks cb, krb5_kdcpreauth_rock rock,
krb5_kdcpreauth_moddata moddata,
krb5_kdcpreauth_verify_respond_fn respond, void *arg)
{
krb5_error_code retval = 0;
krb5_timestamp now;
krb5_enc_data *enc = NULL;
krb5_data scratch, plain;
krb5_keyblock *armor_key = cb->fast_armor(context, rock);
krb5_pa_enc_ts *ts = NULL;
krb5_keyblock *client_keys = NULL;
krb5_keyblock *challenge_key = NULL;
krb5_keyblock *kdc_challenge_key;
krb5_kdcpreauth_modreq modreq = NULL;
int i = 0;
plain.data = NULL;
if (armor_key == NULL) {
retval = ENOENT;
krb5_set_error_message(context, ENOENT,
_("Encrypted Challenge used outside of FAST "
"tunnel"));
}
scratch.data = (char *) data->contents;
scratch.length = data->length;
if (retval == 0)
retval = decode_krb5_enc_data(&scratch, &enc);
if (retval == 0) {
plain.data = malloc(enc->ciphertext.length);
plain.length = enc->ciphertext.length;
if (plain.data == NULL)
retval = ENOMEM;
}
if (retval == 0)
retval = cb->client_keys(context, rock, &client_keys);
if (retval == 0) {
for (i = 0; client_keys[i].enctype&& (retval == 0); i++ ) {
retval = krb5_c_fx_cf2_simple(context,
armor_key, "clientchallengearmor",
&client_keys[i], "challengelongterm",
&challenge_key);
if (retval == 0)
retval = krb5_c_decrypt(context, challenge_key,
KRB5_KEYUSAGE_ENC_CHALLENGE_CLIENT,
NULL, enc, &plain);
if (challenge_key)
krb5_free_keyblock(context, challenge_key);
challenge_key = NULL;
if (retval == 0)
break;
/*We failed to decrypt. Try next key*/
retval = 0;
}
if (client_keys[i].enctype == 0) {
retval = KRB5KDC_ERR_PREAUTH_FAILED;
krb5_set_error_message(context, retval,
_("Incorrect password in encrypted "
"challenge"));
}
}
if (retval == 0)
retval = decode_krb5_pa_enc_ts(&plain, &ts);
if (retval == 0)
retval = krb5_timeofday(context, &now);
if (retval == 0) {
if (labs(now-ts->patimestamp) < context->clockskew) {
enc_tkt_reply->flags |= TKT_FLG_PRE_AUTH;
/*
* If this fails, we won't generate a reply to the client. That
* may cause the client to fail, but at this point the KDC has
* considered this a success, so the return value is ignored.
*/
if (krb5_c_fx_cf2_simple(context, armor_key, "kdcchallengearmor",
&client_keys[i], "challengelongterm",
&kdc_challenge_key) == 0)
modreq = (krb5_kdcpreauth_modreq)kdc_challenge_key;
} else { /*skew*/
retval = KRB5KRB_AP_ERR_SKEW;
}
}
cb->free_keys(context, rock, client_keys);
if (plain.data)
free(plain.data);
if (enc)
krb5_free_enc_data(context, enc);
if (ts)
krb5_free_pa_enc_ts(context, ts);
(*respond)(arg, retval, modreq, NULL, NULL);
}
static void
enc_ts_verify(krb5_context context, krb5_data *req_pkt, krb5_kdc_req *request,
krb5_enc_tkt_part *enc_tkt_reply, krb5_pa_data *pa,
krb5_kdcpreauth_callbacks cb, krb5_kdcpreauth_rock rock,
krb5_kdcpreauth_moddata moddata,
krb5_kdcpreauth_verify_respond_fn respond, void *arg)
{
krb5_pa_enc_ts * pa_enc = 0;
krb5_error_code retval;
krb5_data scratch;
krb5_data enc_ts_data;
krb5_enc_data *enc_data = 0;
krb5_keyblock key;
krb5_key_data * client_key;
krb5_int32 start;
krb5_timestamp timenow;
krb5_error_code decrypt_err = 0;
scratch.data = (char *)pa->contents;
scratch.length = pa->length;
enc_ts_data.data = 0;
if ((retval = decode_krb5_enc_data(&scratch, &enc_data)) != 0)
goto cleanup;
enc_ts_data.length = enc_data->ciphertext.length;
if ((enc_ts_data.data = (char *) malloc(enc_ts_data.length)) == NULL)
goto cleanup;
start = 0;
decrypt_err = 0;
while (1) {
if ((retval = krb5_dbe_search_enctype(context, rock->client,
&start, enc_data->enctype,
-1, 0, &client_key)))
goto cleanup;
if ((retval = krb5_dbe_decrypt_key_data(context, NULL, client_key,
&key, NULL)))
goto cleanup;
key.enctype = enc_data->enctype;
retval = krb5_c_decrypt(context, &key, KRB5_KEYUSAGE_AS_REQ_PA_ENC_TS,
0, enc_data, &enc_ts_data);
krb5_free_keyblock_contents(context, &key);
if (retval == 0)
break;
else
decrypt_err = retval;
}
if ((retval = decode_krb5_pa_enc_ts(&enc_ts_data, &pa_enc)) != 0)
goto cleanup;
if ((retval = krb5_timeofday(context, &timenow)) != 0)
goto cleanup;
if (labs(timenow - pa_enc->patimestamp) > context->clockskew) {
retval = KRB5KRB_AP_ERR_SKEW;
goto cleanup;
}
setflag(enc_tkt_reply->flags, TKT_FLG_PRE_AUTH);
retval = 0;
cleanup:
if (enc_data) {
krb5_free_data_contents(context, &enc_data->ciphertext);
free(enc_data);
}
krb5_free_data_contents(context, &enc_ts_data);
if (pa_enc)
free(pa_enc);
/*
* If we get NO_MATCHING_KEY and decryption previously failed, and
* we failed to find any other keys of the correct enctype after
* that failed decryption, it probably means that the password was
* incorrect.
*/
if (retval == KRB5_KDB_NO_MATCHING_KEY && decrypt_err != 0)
retval = decrypt_err;
(*respond)(arg, retval, NULL, NULL, NULL);
}
static krb5_error_code
ec_process(krb5_context context, krb5_clpreauth_moddata moddata,
krb5_clpreauth_modreq modreq, krb5_get_init_creds_opt *opt,
krb5_clpreauth_callbacks cb,
krb5_clpreauth_rock rock, krb5_kdc_req *request,
krb5_data *encoded_request_body,
krb5_data *encoded_previous_request, krb5_pa_data *padata,
krb5_prompter_fct prompter, void *prompter_data,
krb5_pa_data ***out_padata)
{
krb5_error_code retval = 0;
krb5_keyblock *challenge_key = NULL, *armor_key, *as_key;
armor_key = cb->fast_armor(context, rock);
if (armor_key == NULL)
return ENOENT;
retval = cb->get_as_key(context, rock, &as_key);
if (retval == 0 && padata->length) {
krb5_enc_data *enc = NULL;
krb5_data scratch;
scratch.length = padata->length;
scratch.data = (char *) padata->contents;
retval = krb5_c_fx_cf2_simple(context,armor_key, "kdcchallengearmor",
as_key, "challengelongterm",
&challenge_key);
if (retval == 0)
retval = decode_krb5_enc_data(&scratch, &enc);
scratch.data = NULL;
if (retval == 0) {
scratch.data = malloc(enc->ciphertext.length);
scratch.length = enc->ciphertext.length;
if (scratch.data == NULL)
retval = ENOMEM;
}
if (retval == 0)
retval = krb5_c_decrypt(context, challenge_key,
KRB5_KEYUSAGE_ENC_CHALLENGE_KDC, NULL,
enc, &scratch);
/*
* Per draft 11 of the preauth framework, the client MAY but is not
* required to actually check the timestamp from the KDC other than to
* confirm it decrypts. This code does not perform that check.
*/
if (scratch.data)
krb5_free_data_contents(context, &scratch);
/* If we had a callback to assert that the KDC is verified, we would
* call it here. */
if (enc)
krb5_free_enc_data(context, enc);
} else if (retval == 0) { /*No padata; we send*/
krb5_enc_data enc;
krb5_pa_data **pa = NULL;
krb5_data *encoded_ts = NULL;
krb5_pa_enc_ts ts;
enc.ciphertext.data = NULL;
/* Use the timestamp from the preauth-required error if possible.
* This time should always be secured by the FAST channel. */
retval = cb->get_preauth_time(context, rock, FALSE, &ts.patimestamp,
&ts.pausec);
if (retval == 0)
retval = encode_krb5_pa_enc_ts(&ts, &encoded_ts);
if (retval == 0)
retval = krb5_c_fx_cf2_simple(context,
armor_key, "clientchallengearmor",
as_key, "challengelongterm",
&challenge_key);
if (retval == 0)
retval = krb5_encrypt_helper(context, challenge_key,
KRB5_KEYUSAGE_ENC_CHALLENGE_CLIENT,
encoded_ts, &enc);
if (encoded_ts)
krb5_free_data(context, encoded_ts);
encoded_ts = NULL;
if (retval == 0) {
retval = encode_krb5_enc_data(&enc, &encoded_ts);
krb5_free_data_contents(context, &enc.ciphertext);
}
if (retval == 0) {
pa = calloc(2, sizeof(krb5_pa_data *));
if (pa == NULL)
retval = ENOMEM;
}
if (retval == 0) {
pa[0] = calloc(1, sizeof(krb5_pa_data));
if (pa[0] == NULL)
retval = ENOMEM;
}
if (retval == 0) {
pa[0]->length = encoded_ts->length;
pa[0]->contents = (unsigned char *) encoded_ts->data;
pa[0]->pa_type = KRB5_PADATA_ENCRYPTED_CHALLENGE;
encoded_ts->data = NULL;
*out_padata = pa;
pa = NULL;
}
free(pa);
krb5_free_data(context, encoded_ts);
}
if (challenge_key)
krb5_free_keyblock(context, challenge_key);
return retval;
}
