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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* Copyright (C) 2001, 2002, 2004, 2007, 2008, 2010 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 "prng.h"
#ifdef FORTUNA
extern struct krb5_prng_provider krb5int_prng_fortuna;
const struct krb5_prng_provider *prng = &krb5int_prng_fortuna;
#elif defined(CRYPTO_IMPL_NSS)
#include "prng_nss.h"
const struct krb5_prng_provider *prng = &krb5int_prng_nss;
#else
#include "yarrow.h"
const struct krb5_prng_provider *prng = &krb5int_prng_yarrow;
#endif
/*
* krb5int_prng_init - Returns 0 on success
*/
int
krb5int_prng_init(void)
{
return prng->init();
}
/*
* krb5_c_random_add_entropy - Returns 0 on success
*/
krb5_error_code KRB5_CALLCONV
krb5_c_random_add_entropy(krb5_context context, unsigned int randsource,
const krb5_data *data)
{
return prng->add_entropy(context, randsource, data);
}
/*
* krb5_c_random_seed - Returns 0 on success
*/
krb5_error_code KRB5_CALLCONV
krb5_c_random_seed(krb5_context context, krb5_data *data)
{
return krb5_c_random_add_entropy(context, KRB5_C_RANDSOURCE_OLDAPI, data);
}
/*
* krb5_c_random_make_octets - Returns 0 on success
*/
krb5_error_code KRB5_CALLCONV
krb5_c_random_make_octets(krb5_context context, krb5_data *data)
{
return prng->make_octets(context, data);
}
void
krb5int_prng_cleanup(void)
{
prng->cleanup();
}
/*
* Routines to get entropy from the OS. For UNIX we try /dev/urandom
* and /dev/random. Currently we don't do anything for Windows.
*/
#if defined(_WIN32)
krb5_boolean
k5_get_os_entropy(unsigned char *buf, size_t len)
{
krb5_boolean result;
if (!CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL, 0))
return FALSE;
result = CryptGenRandom(provider, len, buf);
(void)CryptReleaseContext(provider, 0);
return result;
}
krb5_error_code KRB5_CALLCONV
krb5_c_random_os_entropy(krb5_context context, int strong, int *success)
{
int oursuccess = 0;
char buf[1024];
krb5_data data = make_data(buf, sizeof(buf));
if (k5_get_os_entropy(buf, sizeof(buf)) &&
krb5_c_random_add_entropy(context, KRB5_C_RANDSOURCE_OSRAND,
&data) == 0)
oursuccess = 1;
if (success != NULL)
*success = oursuccess;
return 0;
}
#else /* not Windows */
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
/* Open device, ensure that it is not a regular file, and read entropy. Return
* true on success, false on failure. */
static krb5_boolean
read_entropy_from_device(const char *device, unsigned char *buf, size_t len)
{
struct stat sb;
int fd;
unsigned char *bp;
size_t left;
ssize_t count;
krb5_boolean result = FALSE;
fd = open(device, O_RDONLY);
if (fd == -1)
return FALSE;
set_cloexec_fd(fd);
if (fstat(fd, &sb) == -1 || S_ISREG(sb.st_mode))
goto cleanup;
for (bp = buf, left = len; left > 0;) {
count = read(fd, bp, left);
if (count <= 0)
goto cleanup;
left -= count;
bp += count;
}
result = TRUE;
cleanup:
close(fd);
return result;
}
krb5_boolean
k5_get_os_entropy(unsigned char *buf, size_t len)
{
return read_entropy_from_device("/dev/urandom", buf, len);
}
/* Read entropy from device and contribute it to the PRNG. Returns true on
* success. */
static krb5_boolean
add_entropy_from_device(krb5_context context, const char *device)
{
krb5_data data;
unsigned char buf[ENTROPY_BUFSIZE];
if (!read_entropy_from_device(device, buf, sizeof(buf)))
return FALSE;
data = make_data(buf, sizeof(buf));
return (krb5_c_random_add_entropy(context, KRB5_C_RANDSOURCE_OSRAND,
&data) == 0);
}
krb5_error_code KRB5_CALLCONV
krb5_c_random_os_entropy(krb5_context context, int strong, int *success)
{
int unused;
int *oursuccess = (success != NULL) ? success : &unused;
*oursuccess = 0;
/* If we are getting strong data then try that first. We are
guaranteed to cause a reseed of some kind if strong is true and
we have both /dev/random and /dev/urandom. We want the strong
data included in the reseed so we get it first.*/
if (strong) {
if (add_entropy_from_device(context, "/dev/random"))
*oursuccess = 1;
}
if (add_entropy_from_device(context, "/dev/urandom"))
*oursuccess = 1;
return 0;
}
#endif /* not Windows */
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