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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/gssapi/krb5/prf.c */
/*
* Copyright 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 <assert.h>
#include "k5-int.h" /* for zap() */
#include "gssapiP_krb5.h"
#include <stdarg.h>
#ifndef MIN /* Usually found in <sys/param.h>. */
#define MIN(_a,_b) ((_a)<(_b)?(_a):(_b))
#endif
OM_uint32 KRB5_CALLCONV
krb5_gss_pseudo_random(OM_uint32 *minor_status,
gss_ctx_id_t context,
int prf_key,
const gss_buffer_t prf_in,
ssize_t desired_output_len,
gss_buffer_t prf_out)
{
krb5_error_code code;
krb5_key key = NULL;
krb5_gss_ctx_id_t ctx;
int i;
OM_uint32 minor;
size_t prflen;
krb5_data t, ns;
unsigned char *p;
prf_out->length = 0;
prf_out->value = NULL;
t.length = 0;
t.data = NULL;
ns.length = 0;
ns.data = NULL;
ctx = (krb5_gss_ctx_id_t)context;
switch (prf_key) {
case GSS_C_PRF_KEY_FULL:
if (ctx->have_acceptor_subkey) {
key = ctx->acceptor_subkey;
break;
}
/* fallthrough */
case GSS_C_PRF_KEY_PARTIAL:
key = ctx->subkey;
break;
default:
code = EINVAL;
goto cleanup;
}
if (key == NULL) {
code = EINVAL;
goto cleanup;
}
if (desired_output_len == 0)
return GSS_S_COMPLETE;
prf_out->value = k5alloc(desired_output_len, &code);
if (prf_out->value == NULL) {
code = KG_INPUT_TOO_LONG;
goto cleanup;
}
prf_out->length = desired_output_len;
code = krb5_c_prf_length(ctx->k5_context,
krb5_k_key_enctype(ctx->k5_context, key),
&prflen);
if (code != 0)
goto cleanup;
ns.length = 4 + prf_in->length;
ns.data = k5alloc(ns.length, &code);
if (ns.data == NULL) {
code = KG_INPUT_TOO_LONG;
goto cleanup;
}
t.length = prflen;
t.data = k5alloc(t.length, &code);
if (t.data == NULL)
goto cleanup;
memcpy(ns.data + 4, prf_in->value, prf_in->length);
i = 0;
p = (unsigned char *)prf_out->value;
while (desired_output_len > 0) {
store_32_be(i, ns.data);
code = krb5_k_prf(ctx->k5_context, key, &ns, &t);
if (code != 0)
goto cleanup;
memcpy(p, t.data, MIN(t.length, desired_output_len));
p += t.length;
desired_output_len -= t.length;
i++;
}
cleanup:
if (code != 0)
gss_release_buffer(&minor, prf_out);
krb5_free_data_contents(ctx->k5_context, &ns);
krb5_free_data_contents(ctx->k5_context, &t);
*minor_status = (OM_uint32)code;
return (code == 0) ? GSS_S_COMPLETE : GSS_S_FAILURE;
}
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