forked from mirrors/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>
365 lines
8.6 KiB
C
365 lines
8.6 KiB
C
/* mpicoder.c - Coder for the external representation of MPIs
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* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include "mpi-internal.h"
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#define DIM(v) (sizeof(v)/sizeof((v)[0]))
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#define MAX_EXTERN_MPI_BITS 16384
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static uint8_t asn[15] = /* Object ID is 1.3.14.3.2.26 */
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{ 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03,
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0x02, 0x1a, 0x05, 0x00, 0x04, 0x14
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};
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MPI do_encode_md(const void *sha_buffer, unsigned nbits)
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{
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int nframe = (nbits + 7) / 8;
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uint8_t *frame, *fr_pt;
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int i = 0, n;
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size_t asnlen = DIM(asn);
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MPI a = MPI_NULL;
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if (SHA1_DIGEST_LENGTH + asnlen + 4 > nframe)
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pr_info("MPI: can't encode a %d bit MD into a %d bits frame\n",
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(int)(SHA1_DIGEST_LENGTH * 8), (int)nbits);
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/* We encode the MD in this way:
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*
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* 0 A PAD(n bytes) 0 ASN(asnlen bytes) MD(len bytes)
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*
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* PAD consists of FF bytes.
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*/
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frame = kmalloc(nframe, GFP_KERNEL);
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if (!frame)
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return MPI_NULL;
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n = 0;
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frame[n++] = 0;
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frame[n++] = 1; /* block type */
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i = nframe - SHA1_DIGEST_LENGTH - asnlen - 3;
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if (i <= 1) {
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pr_info("MPI: message digest encoding failed\n");
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kfree(frame);
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return a;
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}
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memset(frame + n, 0xff, i);
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n += i;
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frame[n++] = 0;
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memcpy(frame + n, &asn, asnlen);
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n += asnlen;
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memcpy(frame + n, sha_buffer, SHA1_DIGEST_LENGTH);
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n += SHA1_DIGEST_LENGTH;
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i = nframe;
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fr_pt = frame;
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if (n != nframe) {
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printk
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("MPI: message digest encoding failed, frame length is wrong\n");
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kfree(frame);
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return a;
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}
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a = mpi_alloc((nframe + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB);
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mpi_set_buffer(a, frame, nframe, 0);
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kfree(frame);
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return a;
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}
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MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
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{
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const uint8_t *buffer = xbuffer;
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int i, j;
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unsigned nbits, nbytes, nlimbs, nread = 0;
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mpi_limb_t a;
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MPI val = MPI_NULL;
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if (*ret_nread < 2)
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goto leave;
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nbits = buffer[0] << 8 | buffer[1];
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if (nbits > MAX_EXTERN_MPI_BITS) {
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pr_info("MPI: mpi too large (%u bits)\n", nbits);
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goto leave;
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}
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buffer += 2;
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nread = 2;
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nbytes = (nbits + 7) / 8;
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nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
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val = mpi_alloc(nlimbs);
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if (!val)
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return MPI_NULL;
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i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
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i %= BYTES_PER_MPI_LIMB;
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val->nbits = nbits;
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j = val->nlimbs = nlimbs;
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val->sign = 0;
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for (; j > 0; j--) {
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a = 0;
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for (; i < BYTES_PER_MPI_LIMB; i++) {
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if (++nread > *ret_nread) {
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printk
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("MPI: mpi larger than buffer nread=%d ret_nread=%d\n",
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nread, *ret_nread);
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goto leave;
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}
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a <<= 8;
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a |= *buffer++;
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}
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i = 0;
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val->d[j - 1] = a;
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}
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leave:
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*ret_nread = nread;
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return val;
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}
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EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
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/****************
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* Make an mpi from a character string.
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*/
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int mpi_fromstr(MPI val, const char *str)
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{
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int hexmode = 0, sign = 0, prepend_zero = 0, i, j, c, c1, c2;
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unsigned nbits, nbytes, nlimbs;
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mpi_limb_t a;
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if (*str == '-') {
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sign = 1;
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str++;
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}
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if (*str == '0' && str[1] == 'x')
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hexmode = 1;
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else
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return -EINVAL; /* other bases are not yet supported */
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str += 2;
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nbits = strlen(str) * 4;
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if (nbits % 8)
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prepend_zero = 1;
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nbytes = (nbits + 7) / 8;
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nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
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if (val->alloced < nlimbs)
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if (!mpi_resize(val, nlimbs))
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return -ENOMEM;
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i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
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i %= BYTES_PER_MPI_LIMB;
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j = val->nlimbs = nlimbs;
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val->sign = sign;
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for (; j > 0; j--) {
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a = 0;
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for (; i < BYTES_PER_MPI_LIMB; i++) {
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if (prepend_zero) {
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c1 = '0';
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prepend_zero = 0;
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} else
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c1 = *str++;
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assert(c1);
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c2 = *str++;
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assert(c2);
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if (c1 >= '0' && c1 <= '9')
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c = c1 - '0';
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else if (c1 >= 'a' && c1 <= 'f')
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c = c1 - 'a' + 10;
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else if (c1 >= 'A' && c1 <= 'F')
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c = c1 - 'A' + 10;
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else {
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mpi_clear(val);
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return 1;
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}
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c <<= 4;
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if (c2 >= '0' && c2 <= '9')
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c |= c2 - '0';
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else if (c2 >= 'a' && c2 <= 'f')
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c |= c2 - 'a' + 10;
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else if (c2 >= 'A' && c2 <= 'F')
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c |= c2 - 'A' + 10;
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else {
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mpi_clear(val);
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return 1;
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}
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a <<= 8;
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a |= c;
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}
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i = 0;
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val->d[j - 1] = a;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(mpi_fromstr);
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/****************
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* Special function to get the low 8 bytes from an mpi.
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* This can be used as a keyid; KEYID is an 2 element array.
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* Return the low 4 bytes.
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*/
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u32 mpi_get_keyid(const MPI a, u32 *keyid)
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{
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#if BYTES_PER_MPI_LIMB == 4
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if (keyid) {
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keyid[0] = a->nlimbs >= 2 ? a->d[1] : 0;
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keyid[1] = a->nlimbs >= 1 ? a->d[0] : 0;
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}
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return a->nlimbs >= 1 ? a->d[0] : 0;
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#elif BYTES_PER_MPI_LIMB == 8
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if (keyid) {
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keyid[0] = a->nlimbs ? (u32) (a->d[0] >> 32) : 0;
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keyid[1] = a->nlimbs ? (u32) (a->d[0] & 0xffffffff) : 0;
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}
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return a->nlimbs ? (u32) (a->d[0] & 0xffffffff) : 0;
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#else
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#error Make this function work with other LIMB sizes
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#endif
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}
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/****************
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* Return an allocated buffer with the MPI (msb first).
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* NBYTES receives the length of this buffer. Caller must free the
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* return string (This function does return a 0 byte buffer with NBYTES
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* set to zero if the value of A is zero. If sign is not NULL, it will
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* be set to the sign of the A.
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*/
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void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
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{
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uint8_t *p, *buffer;
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mpi_limb_t alimb;
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int i;
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unsigned int n;
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if (sign)
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*sign = a->sign;
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*nbytes = n = a->nlimbs * BYTES_PER_MPI_LIMB;
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if (!n)
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n++; /* avoid zero length allocation */
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p = buffer = kmalloc(n, GFP_KERNEL);
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for (i = a->nlimbs - 1; i >= 0; i--) {
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alimb = a->d[i];
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#if BYTES_PER_MPI_LIMB == 4
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*p++ = alimb >> 24;
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*p++ = alimb >> 16;
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*p++ = alimb >> 8;
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*p++ = alimb;
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#elif BYTES_PER_MPI_LIMB == 8
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*p++ = alimb >> 56;
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*p++ = alimb >> 48;
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*p++ = alimb >> 40;
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*p++ = alimb >> 32;
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*p++ = alimb >> 24;
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*p++ = alimb >> 16;
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*p++ = alimb >> 8;
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*p++ = alimb;
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#else
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#error please implement for this limb size.
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#endif
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}
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/* this is sub-optimal but we need to do the shift operation
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* because the caller has to free the returned buffer */
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for (p = buffer; !*p && *nbytes; p++, --*nbytes)
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;
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if (p != buffer)
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memmove(buffer, p, *nbytes);
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return buffer;
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}
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EXPORT_SYMBOL_GPL(mpi_get_buffer);
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/****************
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* Use BUFFER to update MPI.
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*/
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int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
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{
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const uint8_t *buffer = xbuffer, *p;
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mpi_limb_t alimb;
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int nlimbs;
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int i;
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nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
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if (RESIZE_IF_NEEDED(a, nlimbs) < 0)
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return -ENOMEM;
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a->sign = sign;
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for (i = 0, p = buffer + nbytes - 1; p >= buffer + BYTES_PER_MPI_LIMB;) {
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#if BYTES_PER_MPI_LIMB == 4
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alimb = (mpi_limb_t) *p--;
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alimb |= (mpi_limb_t) *p-- << 8;
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alimb |= (mpi_limb_t) *p-- << 16;
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alimb |= (mpi_limb_t) *p-- << 24;
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#elif BYTES_PER_MPI_LIMB == 8
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alimb = (mpi_limb_t) *p--;
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alimb |= (mpi_limb_t) *p-- << 8;
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alimb |= (mpi_limb_t) *p-- << 16;
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alimb |= (mpi_limb_t) *p-- << 24;
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alimb |= (mpi_limb_t) *p-- << 32;
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alimb |= (mpi_limb_t) *p-- << 40;
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alimb |= (mpi_limb_t) *p-- << 48;
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alimb |= (mpi_limb_t) *p-- << 56;
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#else
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#error please implement for this limb size.
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#endif
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a->d[i++] = alimb;
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}
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if (p >= buffer) {
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#if BYTES_PER_MPI_LIMB == 4
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alimb = *p--;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 8;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 16;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 24;
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#elif BYTES_PER_MPI_LIMB == 8
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alimb = (mpi_limb_t) *p--;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 8;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 16;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 24;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 32;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 40;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 48;
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if (p >= buffer)
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alimb |= (mpi_limb_t) *p-- << 56;
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#else
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#error please implement for this limb size.
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#endif
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a->d[i++] = alimb;
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}
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a->nlimbs = i;
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if (i != nlimbs) {
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pr_emerg("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i,
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nlimbs);
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BUG();
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(mpi_set_buffer);
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