freebsd-dev/sys/kgssapi/krb5/kcrypto.c
Pedro F. Giffuni 55e0987aea sys: extend use of the howmany() macro when available.
We have a howmany() macro in the <sys/param.h> header that is
convenient to re-use as it makes things easier to read.
2016-04-26 15:38:17 +00:00

266 lines
6.5 KiB
C

/*-
* Copyright (c) 2008 Isilon Inc http://www.isilon.com/
* Authors: Doug Rabson <dfr@rabson.org>
* Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/kobj.h>
#include <sys/mbuf.h>
#include <kgssapi/gssapi.h>
#include <kgssapi/gssapi_impl.h>
#include "kcrypto.h"
static struct krb5_encryption_class *krb5_encryption_classes[] = {
&krb5_des_encryption_class,
&krb5_des3_encryption_class,
&krb5_aes128_encryption_class,
&krb5_aes256_encryption_class,
&krb5_arcfour_encryption_class,
&krb5_arcfour_56_encryption_class,
NULL
};
struct krb5_encryption_class *
krb5_find_encryption_class(int etype)
{
int i;
for (i = 0; krb5_encryption_classes[i]; i++) {
if (krb5_encryption_classes[i]->ec_type == etype)
return (krb5_encryption_classes[i]);
}
return (NULL);
}
struct krb5_key_state *
krb5_create_key(const struct krb5_encryption_class *ec)
{
struct krb5_key_state *ks;
ks = malloc(sizeof(struct krb5_key_state), M_GSSAPI, M_WAITOK);
ks->ks_class = ec;
refcount_init(&ks->ks_refs, 1);
ks->ks_key = malloc(ec->ec_keylen, M_GSSAPI, M_WAITOK);
ec->ec_init(ks);
return (ks);
}
void
krb5_free_key(struct krb5_key_state *ks)
{
if (refcount_release(&ks->ks_refs)) {
ks->ks_class->ec_destroy(ks);
bzero(ks->ks_key, ks->ks_class->ec_keylen);
free(ks->ks_key, M_GSSAPI);
free(ks, M_GSSAPI);
}
}
static size_t
gcd(size_t a, size_t b)
{
if (b == 0)
return (a);
return gcd(b, a % b);
}
static size_t
lcm(size_t a, size_t b)
{
return ((a * b) / gcd(a, b));
}
/*
* Rotate right 13 of a variable precision number in 'in', storing the
* result in 'out'. The number is assumed to be big-endian in memory
* representation.
*/
static void
krb5_rotate_right_13(uint8_t *out, uint8_t *in, size_t numlen)
{
uint32_t carry;
size_t i;
/*
* Special case when numlen == 1. A rotate right 13 of a
* single byte number changes to a rotate right 5.
*/
if (numlen == 1) {
carry = in[0] >> 5;
out[0] = (in[0] << 3) | carry;
return;
}
carry = ((in[numlen - 2] & 31) << 8) | in[numlen - 1];
for (i = 2; i < numlen; i++) {
out[i] = ((in[i - 2] & 31) << 3) | (in[i - 1] >> 5);
}
out[1] = ((carry & 31) << 3) | (in[0] >> 5);
out[0] = carry >> 5;
}
/*
* Add two variable precision numbers in big-endian representation
* using ones-complement arithmetic.
*/
static void
krb5_ones_complement_add(uint8_t *out, const uint8_t *in, size_t len)
{
int n, i;
/*
* First calculate the 2s complement sum, remembering the
* carry.
*/
n = 0;
for (i = len - 1; i >= 0; i--) {
n = out[i] + in[i] + n;
out[i] = n;
n >>= 8;
}
/*
* Then add back the carry.
*/
for (i = len - 1; n && i >= 0; i--) {
n = out[i] + n;
out[i] = n;
n >>= 8;
}
}
static void
krb5_n_fold(uint8_t *out, size_t outlen, const uint8_t *in, size_t inlen)
{
size_t tmplen;
uint8_t *tmp;
size_t i;
uint8_t *p;
tmplen = lcm(inlen, outlen);
tmp = malloc(tmplen, M_GSSAPI, M_WAITOK);
bcopy(in, tmp, inlen);
for (i = inlen, p = tmp; i < tmplen; i += inlen, p += inlen) {
krb5_rotate_right_13(p + inlen, p, inlen);
}
bzero(out, outlen);
for (i = 0, p = tmp; i < tmplen; i += outlen, p += outlen) {
krb5_ones_complement_add(out, p, outlen);
}
free(tmp, M_GSSAPI);
}
struct krb5_key_state *
krb5_derive_key(struct krb5_key_state *inkey,
void *constant, size_t constantlen)
{
struct krb5_key_state *dk;
const struct krb5_encryption_class *ec = inkey->ks_class;
uint8_t *folded;
uint8_t *bytes, *p, *q;
struct mbuf *m;
int randomlen, i;
/*
* Expand the constant to blocklen bytes.
*/
folded = malloc(ec->ec_blocklen, M_GSSAPI, M_WAITOK);
krb5_n_fold(folded, ec->ec_blocklen, constant, constantlen);
/*
* Generate enough bytes for keybits rounded up to a multiple
* of blocklen.
*/
randomlen = roundup(ec->ec_keybits / 8, ec->ec_blocklen);
bytes = malloc(randomlen, M_GSSAPI, M_WAITOK);
MGET(m, M_WAITOK, MT_DATA);
m->m_len = ec->ec_blocklen;
for (i = 0, p = bytes, q = folded; i < randomlen;
q = p, i += ec->ec_blocklen, p += ec->ec_blocklen) {
bcopy(q, m->m_data, ec->ec_blocklen);
krb5_encrypt(inkey, m, 0, ec->ec_blocklen, NULL, 0);
bcopy(m->m_data, p, ec->ec_blocklen);
}
m_free(m);
dk = krb5_create_key(ec);
krb5_random_to_key(dk, bytes);
free(folded, M_GSSAPI);
free(bytes, M_GSSAPI);
return (dk);
}
static struct krb5_key_state *
krb5_get_usage_key(struct krb5_key_state *basekey, int usage, int which)
{
const struct krb5_encryption_class *ec = basekey->ks_class;
if (ec->ec_flags & EC_DERIVED_KEYS) {
uint8_t constant[5];
constant[0] = usage >> 24;
constant[1] = usage >> 16;
constant[2] = usage >> 8;
constant[3] = usage;
constant[4] = which;
return (krb5_derive_key(basekey, constant, 5));
} else {
refcount_acquire(&basekey->ks_refs);
return (basekey);
}
}
struct krb5_key_state *
krb5_get_encryption_key(struct krb5_key_state *basekey, int usage)
{
return (krb5_get_usage_key(basekey, usage, 0xaa));
}
struct krb5_key_state *
krb5_get_integrity_key(struct krb5_key_state *basekey, int usage)
{
return (krb5_get_usage_key(basekey, usage, 0x55));
}
struct krb5_key_state *
krb5_get_checksum_key(struct krb5_key_state *basekey, int usage)
{
return (krb5_get_usage_key(basekey, usage, 0x99));
}