55e0987aea
We have a howmany() macro in the <sys/param.h> header that is convenient to re-use as it makes things easier to read.
266 lines
6.5 KiB
C
266 lines
6.5 KiB
C
/*-
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* Copyright (c) 2008 Isilon Inc http://www.isilon.com/
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* Authors: Doug Rabson <dfr@rabson.org>
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* Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/malloc.h>
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#include <sys/kobj.h>
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#include <sys/mbuf.h>
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#include <kgssapi/gssapi.h>
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#include <kgssapi/gssapi_impl.h>
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#include "kcrypto.h"
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static struct krb5_encryption_class *krb5_encryption_classes[] = {
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&krb5_des_encryption_class,
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&krb5_des3_encryption_class,
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&krb5_aes128_encryption_class,
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&krb5_aes256_encryption_class,
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&krb5_arcfour_encryption_class,
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&krb5_arcfour_56_encryption_class,
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NULL
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};
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struct krb5_encryption_class *
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krb5_find_encryption_class(int etype)
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{
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int i;
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for (i = 0; krb5_encryption_classes[i]; i++) {
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if (krb5_encryption_classes[i]->ec_type == etype)
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return (krb5_encryption_classes[i]);
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}
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return (NULL);
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}
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struct krb5_key_state *
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krb5_create_key(const struct krb5_encryption_class *ec)
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{
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struct krb5_key_state *ks;
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ks = malloc(sizeof(struct krb5_key_state), M_GSSAPI, M_WAITOK);
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ks->ks_class = ec;
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refcount_init(&ks->ks_refs, 1);
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ks->ks_key = malloc(ec->ec_keylen, M_GSSAPI, M_WAITOK);
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ec->ec_init(ks);
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return (ks);
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}
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void
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krb5_free_key(struct krb5_key_state *ks)
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{
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if (refcount_release(&ks->ks_refs)) {
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ks->ks_class->ec_destroy(ks);
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bzero(ks->ks_key, ks->ks_class->ec_keylen);
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free(ks->ks_key, M_GSSAPI);
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free(ks, M_GSSAPI);
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}
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}
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static size_t
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gcd(size_t a, size_t b)
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{
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if (b == 0)
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return (a);
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return gcd(b, a % b);
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}
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static size_t
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lcm(size_t a, size_t b)
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{
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return ((a * b) / gcd(a, b));
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}
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/*
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* Rotate right 13 of a variable precision number in 'in', storing the
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* result in 'out'. The number is assumed to be big-endian in memory
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* representation.
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*/
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static void
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krb5_rotate_right_13(uint8_t *out, uint8_t *in, size_t numlen)
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{
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uint32_t carry;
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size_t i;
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/*
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* Special case when numlen == 1. A rotate right 13 of a
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* single byte number changes to a rotate right 5.
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*/
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if (numlen == 1) {
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carry = in[0] >> 5;
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out[0] = (in[0] << 3) | carry;
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return;
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}
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carry = ((in[numlen - 2] & 31) << 8) | in[numlen - 1];
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for (i = 2; i < numlen; i++) {
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out[i] = ((in[i - 2] & 31) << 3) | (in[i - 1] >> 5);
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}
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out[1] = ((carry & 31) << 3) | (in[0] >> 5);
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out[0] = carry >> 5;
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}
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/*
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* Add two variable precision numbers in big-endian representation
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* using ones-complement arithmetic.
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*/
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static void
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krb5_ones_complement_add(uint8_t *out, const uint8_t *in, size_t len)
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{
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int n, i;
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/*
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* First calculate the 2s complement sum, remembering the
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* carry.
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*/
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n = 0;
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for (i = len - 1; i >= 0; i--) {
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n = out[i] + in[i] + n;
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out[i] = n;
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n >>= 8;
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}
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/*
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* Then add back the carry.
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*/
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for (i = len - 1; n && i >= 0; i--) {
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n = out[i] + n;
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out[i] = n;
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n >>= 8;
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}
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}
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static void
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krb5_n_fold(uint8_t *out, size_t outlen, const uint8_t *in, size_t inlen)
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{
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size_t tmplen;
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uint8_t *tmp;
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size_t i;
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uint8_t *p;
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tmplen = lcm(inlen, outlen);
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tmp = malloc(tmplen, M_GSSAPI, M_WAITOK);
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bcopy(in, tmp, inlen);
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for (i = inlen, p = tmp; i < tmplen; i += inlen, p += inlen) {
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krb5_rotate_right_13(p + inlen, p, inlen);
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}
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bzero(out, outlen);
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for (i = 0, p = tmp; i < tmplen; i += outlen, p += outlen) {
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krb5_ones_complement_add(out, p, outlen);
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}
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free(tmp, M_GSSAPI);
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}
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struct krb5_key_state *
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krb5_derive_key(struct krb5_key_state *inkey,
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void *constant, size_t constantlen)
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{
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struct krb5_key_state *dk;
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const struct krb5_encryption_class *ec = inkey->ks_class;
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uint8_t *folded;
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uint8_t *bytes, *p, *q;
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struct mbuf *m;
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int randomlen, i;
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/*
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* Expand the constant to blocklen bytes.
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*/
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folded = malloc(ec->ec_blocklen, M_GSSAPI, M_WAITOK);
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krb5_n_fold(folded, ec->ec_blocklen, constant, constantlen);
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/*
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* Generate enough bytes for keybits rounded up to a multiple
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* of blocklen.
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*/
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randomlen = roundup(ec->ec_keybits / 8, ec->ec_blocklen);
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bytes = malloc(randomlen, M_GSSAPI, M_WAITOK);
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MGET(m, M_WAITOK, MT_DATA);
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m->m_len = ec->ec_blocklen;
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for (i = 0, p = bytes, q = folded; i < randomlen;
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q = p, i += ec->ec_blocklen, p += ec->ec_blocklen) {
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bcopy(q, m->m_data, ec->ec_blocklen);
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krb5_encrypt(inkey, m, 0, ec->ec_blocklen, NULL, 0);
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bcopy(m->m_data, p, ec->ec_blocklen);
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}
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m_free(m);
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dk = krb5_create_key(ec);
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krb5_random_to_key(dk, bytes);
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free(folded, M_GSSAPI);
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free(bytes, M_GSSAPI);
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return (dk);
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}
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static struct krb5_key_state *
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krb5_get_usage_key(struct krb5_key_state *basekey, int usage, int which)
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{
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const struct krb5_encryption_class *ec = basekey->ks_class;
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if (ec->ec_flags & EC_DERIVED_KEYS) {
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uint8_t constant[5];
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constant[0] = usage >> 24;
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constant[1] = usage >> 16;
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constant[2] = usage >> 8;
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constant[3] = usage;
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constant[4] = which;
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return (krb5_derive_key(basekey, constant, 5));
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} else {
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refcount_acquire(&basekey->ks_refs);
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return (basekey);
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}
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}
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struct krb5_key_state *
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krb5_get_encryption_key(struct krb5_key_state *basekey, int usage)
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{
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return (krb5_get_usage_key(basekey, usage, 0xaa));
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}
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struct krb5_key_state *
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krb5_get_integrity_key(struct krb5_key_state *basekey, int usage)
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{
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return (krb5_get_usage_key(basekey, usage, 0x55));
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}
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struct krb5_key_state *
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krb5_get_checksum_key(struct krb5_key_state *basekey, int usage)
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{
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return (krb5_get_usage_key(basekey, usage, 0x99));
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}
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