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crypto: GnuPG based MPI lib - additional sources (part 4)
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. This code is unnecessary for RSA digital signature verification, but for completeness it is included here and can be compiled, if CONFIG_MPILIB_EXTRA is enabled. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
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Dmitry Kasatkin
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7e8dec918e
12 changed files with 1400 additions and 0 deletions
333
lib/mpi/mpi-div.c
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333
lib/mpi/mpi-div.c
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/* mpi-div.c - MPI functions
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* Copyright (C) 1994, 1996 Free Software Foundation, Inc.
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* Copyright (C) 1998, 1999, 2000, 2001 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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* Note: This code is heavily based on the GNU MP Library.
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* Actually it's the same code with only minor changes in the
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* way the data is stored; this is to support the abstraction
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* of an optional secure memory allocation which may be used
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* to avoid revealing of sensitive data due to paging etc.
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* The GNU MP Library itself is published under the LGPL;
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* however I decided to publish this code under the plain GPL.
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*/
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#include <linux/string.h>
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#include "mpi-internal.h"
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#include "longlong.h"
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int mpi_fdiv_r(MPI rem, MPI dividend, MPI divisor)
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{
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int rc = -ENOMEM;
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int divisor_sign = divisor->sign;
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MPI temp_divisor = NULL;
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/* We need the original value of the divisor after the remainder has been
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* preliminary calculated. We have to copy it to temporary space if it's
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* the same variable as REM. */
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if (rem == divisor) {
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if (mpi_copy(&temp_divisor, divisor) < 0)
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goto nomem;
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divisor = temp_divisor;
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}
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if (mpi_tdiv_qr(NULL, rem, dividend, divisor) < 0)
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goto nomem;
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if (((divisor_sign ? 1 : 0) ^ (dividend->sign ? 1 : 0)) && rem->nlimbs)
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if (mpi_add(rem, rem, divisor) < 0)
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goto nomem;
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rc = 0;
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nomem:
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if (temp_divisor)
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mpi_free(temp_divisor);
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return rc;
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}
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/****************
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* Division rounding the quotient towards -infinity.
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* The remainder gets the same sign as the denominator.
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* rem is optional
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*/
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ulong mpi_fdiv_r_ui(MPI rem, MPI dividend, ulong divisor)
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{
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mpi_limb_t rlimb;
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rlimb = mpihelp_mod_1(dividend->d, dividend->nlimbs, divisor);
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if (rlimb && dividend->sign)
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rlimb = divisor - rlimb;
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if (rem) {
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rem->d[0] = rlimb;
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rem->nlimbs = rlimb ? 1 : 0;
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}
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return rlimb;
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}
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int mpi_fdiv_q(MPI quot, MPI dividend, MPI divisor)
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{
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MPI tmp = mpi_alloc(mpi_get_nlimbs(quot));
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if (!tmp)
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return -ENOMEM;
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mpi_fdiv_qr(quot, tmp, dividend, divisor);
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mpi_free(tmp);
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return 0;
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}
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int mpi_fdiv_qr(MPI quot, MPI rem, MPI dividend, MPI divisor)
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{
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int divisor_sign = divisor->sign;
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MPI temp_divisor = NULL;
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if (quot == divisor || rem == divisor) {
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if (mpi_copy(&temp_divisor, divisor) < 0)
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return -ENOMEM;
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divisor = temp_divisor;
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}
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if (mpi_tdiv_qr(quot, rem, dividend, divisor) < 0)
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goto nomem;
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if ((divisor_sign ^ dividend->sign) && rem->nlimbs) {
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if (mpi_sub_ui(quot, quot, 1) < 0)
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goto nomem;
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if (mpi_add(rem, rem, divisor) < 0)
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goto nomem;
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}
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if (temp_divisor)
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mpi_free(temp_divisor);
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return 0;
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nomem:
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mpi_free(temp_divisor);
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return -ENOMEM;
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}
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/* If den == quot, den needs temporary storage.
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* If den == rem, den needs temporary storage.
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* If num == quot, num needs temporary storage.
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* If den has temporary storage, it can be normalized while being copied,
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* i.e no extra storage should be allocated.
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*/
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int mpi_tdiv_r(MPI rem, MPI num, MPI den)
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{
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return mpi_tdiv_qr(NULL, rem, num, den);
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}
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int mpi_tdiv_qr(MPI quot, MPI rem, MPI num, MPI den)
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{
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int rc = -ENOMEM;
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mpi_ptr_t np, dp;
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mpi_ptr_t qp, rp;
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mpi_size_t nsize = num->nlimbs;
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mpi_size_t dsize = den->nlimbs;
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mpi_size_t qsize, rsize;
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mpi_size_t sign_remainder = num->sign;
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mpi_size_t sign_quotient = num->sign ^ den->sign;
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unsigned normalization_steps;
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mpi_limb_t q_limb;
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mpi_ptr_t marker[5];
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int markidx = 0;
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memset(marker, 0, sizeof(marker));
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/* Ensure space is enough for quotient and remainder.
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* We need space for an extra limb in the remainder, because it's
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* up-shifted (normalized) below. */
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rsize = nsize + 1;
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if (mpi_resize(rem, rsize) < 0)
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goto nomem;
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qsize = rsize - dsize; /* qsize cannot be bigger than this. */
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if (qsize <= 0) {
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if (num != rem) {
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rem->nlimbs = num->nlimbs;
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rem->sign = num->sign;
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MPN_COPY(rem->d, num->d, nsize);
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}
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if (quot) {
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/* This needs to follow the assignment to rem, in case the
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* numerator and quotient are the same. */
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quot->nlimbs = 0;
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quot->sign = 0;
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}
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return 0;
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}
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if (quot)
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if (mpi_resize(quot, qsize) < 0)
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goto nomem;
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/* Read pointers here, when reallocation is finished. */
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np = num->d;
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dp = den->d;
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rp = rem->d;
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/* Optimize division by a single-limb divisor. */
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if (dsize == 1) {
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mpi_limb_t rlimb;
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if (quot) {
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qp = quot->d;
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rlimb = mpihelp_divmod_1(qp, np, nsize, dp[0]);
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qsize -= qp[qsize - 1] == 0;
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quot->nlimbs = qsize;
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quot->sign = sign_quotient;
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} else
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rlimb = mpihelp_mod_1(np, nsize, dp[0]);
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rp[0] = rlimb;
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rsize = rlimb != 0 ? 1 : 0;
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rem->nlimbs = rsize;
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rem->sign = sign_remainder;
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return 0;
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}
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if (quot) {
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qp = quot->d;
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/* Make sure QP and NP point to different objects. Otherwise the
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* numerator would be gradually overwritten by the quotient limbs. */
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if (qp == np) { /* Copy NP object to temporary space. */
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np = marker[markidx++] = mpi_alloc_limb_space(nsize);
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MPN_COPY(np, qp, nsize);
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}
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} else /* Put quotient at top of remainder. */
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qp = rp + dsize;
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count_leading_zeros(normalization_steps, dp[dsize - 1]);
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/* Normalize the denominator, i.e. make its most significant bit set by
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* shifting it NORMALIZATION_STEPS bits to the left. Also shift the
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* numerator the same number of steps (to keep the quotient the same!).
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*/
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if (normalization_steps) {
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mpi_ptr_t tp;
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mpi_limb_t nlimb;
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/* Shift up the denominator setting the most significant bit of
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* the most significant word. Use temporary storage not to clobber
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* the original contents of the denominator. */
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tp = marker[markidx++] = mpi_alloc_limb_space(dsize);
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if (!tp)
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goto nomem;
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mpihelp_lshift(tp, dp, dsize, normalization_steps);
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dp = tp;
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/* Shift up the numerator, possibly introducing a new most
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* significant word. Move the shifted numerator in the remainder
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* meanwhile. */
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nlimb = mpihelp_lshift(rp, np, nsize, normalization_steps);
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if (nlimb) {
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rp[nsize] = nlimb;
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rsize = nsize + 1;
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} else
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rsize = nsize;
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} else {
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/* The denominator is already normalized, as required. Copy it to
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* temporary space if it overlaps with the quotient or remainder. */
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if (dp == rp || (quot && (dp == qp))) {
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mpi_ptr_t tp;
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tp = marker[markidx++] = mpi_alloc_limb_space(dsize);
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if (!tp)
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goto nomem;
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MPN_COPY(tp, dp, dsize);
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dp = tp;
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}
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/* Move the numerator to the remainder. */
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if (rp != np)
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MPN_COPY(rp, np, nsize);
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rsize = nsize;
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}
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q_limb = mpihelp_divrem(qp, 0, rp, rsize, dp, dsize);
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if (quot) {
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qsize = rsize - dsize;
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if (q_limb) {
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qp[qsize] = q_limb;
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qsize += 1;
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}
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quot->nlimbs = qsize;
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quot->sign = sign_quotient;
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}
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rsize = dsize;
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MPN_NORMALIZE(rp, rsize);
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if (normalization_steps && rsize) {
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mpihelp_rshift(rp, rp, rsize, normalization_steps);
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rsize -= rp[rsize - 1] == 0 ? 1 : 0;
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}
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rem->nlimbs = rsize;
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rem->sign = sign_remainder;
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rc = 0;
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nomem:
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while (markidx)
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mpi_free_limb_space(marker[--markidx]);
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return rc;
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}
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int mpi_tdiv_q_2exp(MPI w, MPI u, unsigned count)
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{
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mpi_size_t usize, wsize;
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mpi_size_t limb_cnt;
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usize = u->nlimbs;
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limb_cnt = count / BITS_PER_MPI_LIMB;
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wsize = usize - limb_cnt;
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if (limb_cnt >= usize)
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w->nlimbs = 0;
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else {
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mpi_ptr_t wp;
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mpi_ptr_t up;
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if (RESIZE_IF_NEEDED(w, wsize) < 0)
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return -ENOMEM;
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wp = w->d;
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up = u->d;
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count %= BITS_PER_MPI_LIMB;
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if (count) {
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mpihelp_rshift(wp, up + limb_cnt, wsize, count);
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wsize -= !wp[wsize - 1];
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} else {
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MPN_COPY_INCR(wp, up + limb_cnt, wsize);
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}
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w->nlimbs = wsize;
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}
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return 0;
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}
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/****************
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* Check whether dividend is divisible by divisor
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* (note: divisor must fit into a limb)
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*/
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int mpi_divisible_ui(MPI dividend, ulong divisor)
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{
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return !mpihelp_mod_1(dividend->d, dividend->nlimbs, divisor);
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}
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