forked from Minki/linux
cdec9cb516
Adds the multi-precision-integer maths library which was originally taken from GnuPG and ported to the kernel by (among others) David Howells. This version is taken from Fedora kernel 2.6.32-71.14.1.el6. The difference is that checkpatch reported errors and warnings have been fixed. This library is used to implemenet RSA digital signature verification used in IMA/EVM integrity protection subsystem. Due to patch size limitation, the patch is divided into 4 parts. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
366 lines
8.6 KiB
C
366 lines
8.6 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 "mpi-internal.h"
|
|
|
|
#define DIM(v) (sizeof(v)/sizeof((v)[0]))
|
|
#define MAX_EXTERN_MPI_BITS 16384
|
|
|
|
static uint8_t asn[15] = /* Object ID is 1.3.14.3.2.26 */
|
|
{ 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03,
|
|
0x02, 0x1a, 0x05, 0x00, 0x04, 0x14
|
|
};
|
|
|
|
MPI do_encode_md(const void *sha_buffer, unsigned nbits)
|
|
{
|
|
int nframe = (nbits + 7) / 8;
|
|
uint8_t *frame, *fr_pt;
|
|
int i = 0, n;
|
|
size_t asnlen = DIM(asn);
|
|
MPI a = MPI_NULL;
|
|
|
|
if (SHA1_DIGEST_LENGTH + asnlen + 4 > nframe)
|
|
pr_info("MPI: can't encode a %d bit MD into a %d bits frame\n",
|
|
(int)(SHA1_DIGEST_LENGTH * 8), (int)nbits);
|
|
|
|
/* We encode the MD in this way:
|
|
*
|
|
* 0 A PAD(n bytes) 0 ASN(asnlen bytes) MD(len bytes)
|
|
*
|
|
* PAD consists of FF bytes.
|
|
*/
|
|
frame = kmalloc(nframe, GFP_KERNEL);
|
|
if (!frame)
|
|
return MPI_NULL;
|
|
n = 0;
|
|
frame[n++] = 0;
|
|
frame[n++] = 1; /* block type */
|
|
i = nframe - SHA1_DIGEST_LENGTH - asnlen - 3;
|
|
|
|
if (i <= 1) {
|
|
pr_info("MPI: message digest encoding failed\n");
|
|
kfree(frame);
|
|
return a;
|
|
}
|
|
|
|
memset(frame + n, 0xff, i);
|
|
n += i;
|
|
frame[n++] = 0;
|
|
memcpy(frame + n, &asn, asnlen);
|
|
n += asnlen;
|
|
memcpy(frame + n, sha_buffer, SHA1_DIGEST_LENGTH);
|
|
n += SHA1_DIGEST_LENGTH;
|
|
|
|
i = nframe;
|
|
fr_pt = frame;
|
|
|
|
if (n != nframe) {
|
|
printk
|
|
("MPI: message digest encoding failed, frame length is wrong\n");
|
|
kfree(frame);
|
|
return a;
|
|
}
|
|
|
|
a = mpi_alloc((nframe + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB);
|
|
mpi_set_buffer(a, frame, nframe, 0);
|
|
kfree(frame);
|
|
|
|
return a;
|
|
}
|
|
|
|
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 = MPI_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 = (nbits + 7) / 8;
|
|
nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
|
|
val = mpi_alloc(nlimbs);
|
|
if (!val)
|
|
return MPI_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);
|
|
|
|
/****************
|
|
* Make an mpi from a character string.
|
|
*/
|
|
int mpi_fromstr(MPI val, const char *str)
|
|
{
|
|
int hexmode = 0, sign = 0, prepend_zero = 0, i, j, c, c1, c2;
|
|
unsigned nbits, nbytes, nlimbs;
|
|
mpi_limb_t a;
|
|
|
|
if (*str == '-') {
|
|
sign = 1;
|
|
str++;
|
|
}
|
|
if (*str == '0' && str[1] == 'x')
|
|
hexmode = 1;
|
|
else
|
|
return -EINVAL; /* other bases are not yet supported */
|
|
str += 2;
|
|
|
|
nbits = strlen(str) * 4;
|
|
if (nbits % 8)
|
|
prepend_zero = 1;
|
|
nbytes = (nbits + 7) / 8;
|
|
nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
|
|
if (val->alloced < nlimbs)
|
|
if (!mpi_resize(val, nlimbs))
|
|
return -ENOMEM;
|
|
i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
|
|
i %= BYTES_PER_MPI_LIMB;
|
|
j = val->nlimbs = nlimbs;
|
|
val->sign = sign;
|
|
for (; j > 0; j--) {
|
|
a = 0;
|
|
for (; i < BYTES_PER_MPI_LIMB; i++) {
|
|
if (prepend_zero) {
|
|
c1 = '0';
|
|
prepend_zero = 0;
|
|
} else
|
|
c1 = *str++;
|
|
assert(c1);
|
|
c2 = *str++;
|
|
assert(c2);
|
|
if (c1 >= '0' && c1 <= '9')
|
|
c = c1 - '0';
|
|
else if (c1 >= 'a' && c1 <= 'f')
|
|
c = c1 - 'a' + 10;
|
|
else if (c1 >= 'A' && c1 <= 'F')
|
|
c = c1 - 'A' + 10;
|
|
else {
|
|
mpi_clear(val);
|
|
return 1;
|
|
}
|
|
c <<= 4;
|
|
if (c2 >= '0' && c2 <= '9')
|
|
c |= c2 - '0';
|
|
else if (c2 >= 'a' && c2 <= 'f')
|
|
c |= c2 - 'a' + 10;
|
|
else if (c2 >= 'A' && c2 <= 'F')
|
|
c |= c2 - 'A' + 10;
|
|
else {
|
|
mpi_clear(val);
|
|
return 1;
|
|
}
|
|
a <<= 8;
|
|
a |= c;
|
|
}
|
|
i = 0;
|
|
|
|
val->d[j - 1] = a;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(mpi_fromstr);
|
|
|
|
/****************
|
|
* Special function to get the low 8 bytes from an mpi.
|
|
* This can be used as a keyid; KEYID is an 2 element array.
|
|
* Return the low 4 bytes.
|
|
*/
|
|
u32 mpi_get_keyid(const MPI a, u32 *keyid)
|
|
{
|
|
#if BYTES_PER_MPI_LIMB == 4
|
|
if (keyid) {
|
|
keyid[0] = a->nlimbs >= 2 ? a->d[1] : 0;
|
|
keyid[1] = a->nlimbs >= 1 ? a->d[0] : 0;
|
|
}
|
|
return a->nlimbs >= 1 ? a->d[0] : 0;
|
|
#elif BYTES_PER_MPI_LIMB == 8
|
|
if (keyid) {
|
|
keyid[0] = a->nlimbs ? (u32) (a->d[0] >> 32) : 0;
|
|
keyid[1] = a->nlimbs ? (u32) (a->d[0] & 0xffffffff) : 0;
|
|
}
|
|
return a->nlimbs ? (u32) (a->d[0] & 0xffffffff) : 0;
|
|
#else
|
|
#error Make this function work with other LIMB sizes
|
|
#endif
|
|
}
|
|
|
|
/****************
|
|
* 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);
|
|
|
|
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 = (nbytes + BYTES_PER_MPI_LIMB - 1) / 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);
|