261 lines
6.2 KiB
C
261 lines
6.2 KiB
C
/* mpicoder.c - Coder for the external representation of MPIs
|
|
* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
|
|
*
|
|
* This file is part of GnuPG.
|
|
*
|
|
* GnuPG is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GnuPG is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
|
|
*/
|
|
|
|
#include <linux/bitops.h>
|
|
#include <asm-generic/bitops/count_zeros.h>
|
|
#include "mpi-internal.h"
|
|
|
|
#define MAX_EXTERN_MPI_BITS 16384
|
|
|
|
/**
|
|
* mpi_read_raw_data - Read a raw byte stream as a positive integer
|
|
* @xbuffer: The data to read
|
|
* @nbytes: The amount of data to read
|
|
*/
|
|
MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes)
|
|
{
|
|
const uint8_t *buffer = xbuffer;
|
|
int i, j;
|
|
unsigned nbits, nlimbs;
|
|
mpi_limb_t a;
|
|
MPI val = NULL;
|
|
|
|
while (nbytes >= 0 && buffer[0] == 0) {
|
|
buffer++;
|
|
nbytes--;
|
|
}
|
|
|
|
nbits = nbytes * 8;
|
|
if (nbits > MAX_EXTERN_MPI_BITS) {
|
|
pr_info("MPI: mpi too large (%u bits)\n", nbits);
|
|
return NULL;
|
|
}
|
|
if (nbytes > 0)
|
|
nbits -= count_leading_zeros(buffer[0]);
|
|
else
|
|
nbits = 0;
|
|
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
val = mpi_alloc(nlimbs);
|
|
if (!val)
|
|
return NULL;
|
|
val->nbits = nbits;
|
|
val->sign = 0;
|
|
val->nlimbs = nlimbs;
|
|
|
|
if (nbytes > 0) {
|
|
i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
|
|
i %= BYTES_PER_MPI_LIMB;
|
|
for (j = nlimbs; j > 0; j--) {
|
|
a = 0;
|
|
for (; i < BYTES_PER_MPI_LIMB; i++) {
|
|
a <<= 8;
|
|
a |= *buffer++;
|
|
}
|
|
i = 0;
|
|
val->d[j - 1] = a;
|
|
}
|
|
}
|
|
return val;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_read_raw_data);
|
|
|
|
MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
|
|
{
|
|
const uint8_t *buffer = xbuffer;
|
|
int i, j;
|
|
unsigned nbits, nbytes, nlimbs, nread = 0;
|
|
mpi_limb_t a;
|
|
MPI val = NULL;
|
|
|
|
if (*ret_nread < 2)
|
|
goto leave;
|
|
nbits = buffer[0] << 8 | buffer[1];
|
|
|
|
if (nbits > MAX_EXTERN_MPI_BITS) {
|
|
pr_info("MPI: mpi too large (%u bits)\n", nbits);
|
|
goto leave;
|
|
}
|
|
buffer += 2;
|
|
nread = 2;
|
|
|
|
nbytes = DIV_ROUND_UP(nbits, 8);
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
val = mpi_alloc(nlimbs);
|
|
if (!val)
|
|
return NULL;
|
|
i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
|
|
i %= BYTES_PER_MPI_LIMB;
|
|
val->nbits = nbits;
|
|
j = val->nlimbs = nlimbs;
|
|
val->sign = 0;
|
|
for (; j > 0; j--) {
|
|
a = 0;
|
|
for (; i < BYTES_PER_MPI_LIMB; i++) {
|
|
if (++nread > *ret_nread) {
|
|
printk
|
|
("MPI: mpi larger than buffer nread=%d ret_nread=%d\n",
|
|
nread, *ret_nread);
|
|
goto leave;
|
|
}
|
|
a <<= 8;
|
|
a |= *buffer++;
|
|
}
|
|
i = 0;
|
|
val->d[j - 1] = a;
|
|
}
|
|
|
|
leave:
|
|
*ret_nread = nread;
|
|
return val;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
|
|
|
|
/****************
|
|
* Return an allocated buffer with the MPI (msb first).
|
|
* NBYTES receives the length of this buffer. Caller must free the
|
|
* return string (This function does return a 0 byte buffer with NBYTES
|
|
* set to zero if the value of A is zero. If sign is not NULL, it will
|
|
* be set to the sign of the A.
|
|
*/
|
|
void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
|
|
{
|
|
uint8_t *p, *buffer;
|
|
mpi_limb_t alimb;
|
|
int i;
|
|
unsigned int n;
|
|
|
|
if (sign)
|
|
*sign = a->sign;
|
|
*nbytes = n = a->nlimbs * BYTES_PER_MPI_LIMB;
|
|
if (!n)
|
|
n++; /* avoid zero length allocation */
|
|
p = buffer = kmalloc(n, GFP_KERNEL);
|
|
if (!p)
|
|
return NULL;
|
|
|
|
for (i = a->nlimbs - 1; i >= 0; i--) {
|
|
alimb = a->d[i];
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
*p++ = alimb >> 24;
|
|
*p++ = alimb >> 16;
|
|
*p++ = alimb >> 8;
|
|
*p++ = alimb;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
*p++ = alimb >> 56;
|
|
*p++ = alimb >> 48;
|
|
*p++ = alimb >> 40;
|
|
*p++ = alimb >> 32;
|
|
*p++ = alimb >> 24;
|
|
*p++ = alimb >> 16;
|
|
*p++ = alimb >> 8;
|
|
*p++ = alimb;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
}
|
|
|
|
/* this is sub-optimal but we need to do the shift operation
|
|
* because the caller has to free the returned buffer */
|
|
for (p = buffer; !*p && *nbytes; p++, --*nbytes)
|
|
;
|
|
if (p != buffer)
|
|
memmove(buffer, p, *nbytes);
|
|
|
|
return buffer;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_get_buffer);
|
|
|
|
/****************
|
|
* Use BUFFER to update MPI.
|
|
*/
|
|
int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
|
|
{
|
|
const uint8_t *buffer = xbuffer, *p;
|
|
mpi_limb_t alimb;
|
|
int nlimbs;
|
|
int i;
|
|
|
|
nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
|
|
if (RESIZE_IF_NEEDED(a, nlimbs) < 0)
|
|
return -ENOMEM;
|
|
a->sign = sign;
|
|
|
|
for (i = 0, p = buffer + nbytes - 1; p >= buffer + BYTES_PER_MPI_LIMB;) {
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
alimb = (mpi_limb_t) *p--;
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
alimb = (mpi_limb_t) *p--;
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
alimb |= (mpi_limb_t) *p-- << 32;
|
|
alimb |= (mpi_limb_t) *p-- << 40;
|
|
alimb |= (mpi_limb_t) *p-- << 48;
|
|
alimb |= (mpi_limb_t) *p-- << 56;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
a->d[i++] = alimb;
|
|
}
|
|
if (p >= buffer) {
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
alimb = *p--;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
alimb = (mpi_limb_t) *p--;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 8;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 16;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 24;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 32;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 40;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 48;
|
|
if (p >= buffer)
|
|
alimb |= (mpi_limb_t) *p-- << 56;
|
|
#else
|
|
#error please implement for this limb size.
|
|
#endif
|
|
a->d[i++] = alimb;
|
|
}
|
|
a->nlimbs = i;
|
|
|
|
if (i != nlimbs) {
|
|
pr_emerg("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i,
|
|
nlimbs);
|
|
BUG();
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_set_buffer);
|