/*
* COPYRIGHT (c) 2008
* The Regents of the University of Michigan
* ALL RIGHTS RESERVED
*
* Permission is granted to use, copy, create derivative works
* and redistribute this software and such derivative works
* for any purpose, so long as the name of The University of
* Michigan is not used in any advertising or publicity
* pertaining to the use of distribution of this software
* without specific, written prior authorization. If the
* above copyright notice or any other identification of the
* University of Michigan is included in any copy of any
* portion of this software, then the disclaimer below must
* also be included.
*
* THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
* FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
* PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
* MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
* WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
* REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
* FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
* CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
* OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
* IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGES.
*/
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* 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 FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <linux/err.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/sunrpc/xdr.h>
#include <linux/lcm.h>
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
/*
* This is the n-fold function as described in rfc3961, sec 5.1
* Taken from MIT Kerberos and modified.
*/
static void krb5_nfold(u32 inbits, const u8 *in,
u32 outbits, u8 *out)
{
unsigned long ulcm;
int byte, i, msbit;
/* the code below is more readable if I make these bytes
instead of bits */
inbits >>= 3;
outbits >>= 3;
/* first compute lcm(n,k) */
ulcm = lcm(inbits, outbits);
/* now do the real work */
memset(out, 0, outbits);
byte = 0;
/* this will end up cycling through k lcm(k,n)/k times, which
is correct */
for (i = ulcm-1; i >= 0; i--) {
/* compute the msbit in k which gets added into this byte */
msbit = (
/* first, start with the msbit in the first,
* unrotated byte */
((inbits << 3) - 1)
/* then, for each byte, shift to the right
* for each repetition */
+ (((inbits << 3) + 13) * (i/inbits))
/* last, pick out the correct byte within
* that shifted repetition */
+ ((inbits - (i % inbits)) << 3)
) % (inbits << 3);
/* pull out the byte value itself */
byte += (((in[((inbits - 1) - (msbit >> 3)) % inbits] << 8)|
(in[((inbits) - (msbit >> 3)) % inbits]))
>> ((msbit & 7) + 1)) & 0xff;
/* do the addition */
byte += out[i % outbits];
out[i % outbits] = byte & 0xff;
/* keep around the carry bit, if any */
byte >>= 8;
}
/* if there's a carry bit left over, add it back in */
if (byte) {
for (i = outbits - 1; i >= 0; i--) {
/* do the addition */
byte += out[i];
out[i] = byte & 0xff;
/* keep around the carry bit, if any */
byte >>= 8;
}
}
}
/*
* This is the DK (derive_key) function as described in rfc3961, sec 5.1
* Taken from MIT Kerberos and modified.
*/
u32 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
const struct xdr_netobj *inkey,
struct xdr_netobj *outkey,
const struct xdr_netobj *in_constant,
gfp_t gfp_mask)
{
size_t blocksize, keybytes, keylength, n;
unsigned char *inblockdata, *outblockdata, *rawkey;
struct xdr_netobj inblock, outblock;
struct crypto_blkcipher *cipher;
u32 ret = EINVAL;
blocksize = gk5e->blocksize;
keybytes = gk5e->keybytes;
keylength = gk5e->keylength;
if ((inkey->len != keylength) || (outkey->len != keylength))
goto err_return;
cipher = crypto_alloc_blkcipher(gk5e->encrypt_name, 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(cipher))
goto err_return;
if (crypto_blkcipher_setkey(cipher, inkey->data, inkey->len))
goto err_return;
/* allocate and set up buffers */
ret = ENOMEM;
inblockdata = kmalloc(blocksize, gfp_mask);
if (inblockdata == NULL)
goto err_free_cipher;
outblockdata = kmalloc(blocksize, gfp_mask);
if (outblockdata == NULL)
goto err_free_in;
rawkey = kmalloc(keybytes, gfp_mask);
if (rawkey == NULL)
goto err_free_out;
inblock.data = (char *) inblockdata;
inblock.len = blocksize;
outblock.data = (char *) outblockdata;
outblock.len = blocksize;
/* initialize the input block */
if (in_constant->len == inblock.len) {
memcpy(inblock.data, in_constant->data, inblock.len);
} else {
krb5_nfold(in_constant->len * 8, in_constant->data,
inblock.len * 8, inblock.data);
}
/* loop encrypting the blocks until enough key bytes are generated */
n = 0;
while (n < keybytes) {
(*(gk5e->encrypt))(cipher, NULL, inblock.data,
outblock.data, inblock.len);
if ((keybytes - n) <= outblock.len) {
memcpy(rawkey + n, outblock.data, (keybytes - n));
break;
}
memcpy(rawkey + n, outblock.data, outblock.len);
memcpy(inblock.data, outblock.data, outblock.len);
n += outblock.len;
}
/* postprocess the key */
inblock.data = (char *) rawkey;
inblock.len = keybytes;
BUG_ON(gk5e->mk_key == NULL);
ret = (*(gk5e->mk_key))(gk5e, &inblock, outkey);
if (ret) {
dprintk("%s: got %d from mk_key function for '%s'\n",
__func__, ret, gk5e->encrypt_name);
goto err_free_raw;
}
/* clean memory, free resources and exit */
ret = 0;
err_free_raw:
memset(rawkey, 0, keybytes);
kfree(rawkey);
err_free_out:
memset(outblockdata, 0, blocksize);
kfree(outblockdata);
err_free_in:
memset(inblockdata, 0, blocksize);
kfree(inblockdata);
err_free_cipher:
crypto_free_blkcipher(cipher);
err_return:
return ret;
}
#define smask(step) ((1<<step)-1)
#define pstep(x, step) (((x)&smask(step))^(((x)>>step)&smask(step)))
#define parity_char(x) pstep(pstep(pstep((x), 4), 2), 1)
static void mit_des_fixup_key_parity(u8 key[8])
{
int i;
for (i = 0; i < 8; i++) {
key[i] &= 0xfe;
key[i] |= 1^parity_char(key[i]);
}
}
/*
* This is the des3 key derivation postprocess function
*/
u32 gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key)
{
int i;
u32 ret = EINVAL;
if (key->len != 24) {
dprintk("%s: key->len is %d\n", __func__, key->len);
goto err_out;
}
if (randombits->len != 21) {
dprintk("%s: randombits->len is %d\n",
__func__, randombits->len);
goto err_out;
}
/* take the seven bytes, move them around into the top 7 bits of the
8 key bytes, then compute the parity bits. Do this three times. */
for (i = 0; i < 3; i++) {
memcpy(key->data + i*8, randombits->data + i*7, 7);
key->data[i*8+7] = (((key->data[i*8]&1)<<1) |
((key->data[i*8+1]&1)<<2) |
((key->data[i*8+2]&1)<<3) |
((key->data[i*8+3]&1)<<4) |
((key->data[i*8+4]&1)<<5) |
((key->data[i*8+5]&1)<<6) |
((key->data[i*8+6]&1)<<7));
mit_des_fixup_key_parity(key->data + i*8);
}
ret = 0;
err_out:
return ret;
}
/*
* This is the aes key derivation postprocess function
*/
u32 gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
struct xdr_netobj *randombits,
struct xdr_netobj *key)
{
u32 ret = EINVAL;
if (key->len != 16 && key->len != 32) {
dprintk("%s: key->len is %d\n", __func__, key->len);
goto err_out;
}
if (randombits->len != 16 && randombits->len != 32) {
dprintk("%s: randombits->len is %d\n",
__func__, randombits->len);
goto err_out;
}
if (randombits->len != key->len) {
dprintk("%s: randombits->len is %d, key->len is %d\n",
__func__, randombits->len, key->len);
goto err_out;
}
memcpy(key->data, randombits->data, key->len);
ret = 0;
err_out:
return ret;
}