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>
diff --git a/lib/mpi/mpi-div.c b/lib/mpi/mpi-div.c
new file mode 100644
index 0000000..c3087d1
--- /dev/null
+++ b/lib/mpi/mpi-div.c
@@ -0,0 +1,333 @@
+/* mpi-div.c - MPI functions
+ * Copyright (C) 1994, 1996 Free Software Foundation, Inc.
+ * Copyright (C) 1998, 1999, 2000, 2001 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
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ * Actually it's the same code with only minor changes in the
+ * way the data is stored; this is to support the abstraction
+ * of an optional secure memory allocation which may be used
+ * to avoid revealing of sensitive data due to paging etc.
+ * The GNU MP Library itself is published under the LGPL;
+ * however I decided to publish this code under the plain GPL.
+ */
+
+#include <linux/string.h>
+#include "mpi-internal.h"
+#include "longlong.h"
+
+int mpi_fdiv_r(MPI rem, MPI dividend, MPI divisor)
+{
+ int rc = -ENOMEM;
+ int divisor_sign = divisor->sign;
+ MPI temp_divisor = NULL;
+
+ /* We need the original value of the divisor after the remainder has been
+ * preliminary calculated. We have to copy it to temporary space if it's
+ * the same variable as REM. */
+ if (rem == divisor) {
+ if (mpi_copy(&temp_divisor, divisor) < 0)
+ goto nomem;
+ divisor = temp_divisor;
+ }
+
+ if (mpi_tdiv_qr(NULL, rem, dividend, divisor) < 0)
+ goto nomem;
+ if (((divisor_sign ? 1 : 0) ^ (dividend->sign ? 1 : 0)) && rem->nlimbs)
+ if (mpi_add(rem, rem, divisor) < 0)
+ goto nomem;
+
+ rc = 0;
+
+nomem:
+ if (temp_divisor)
+ mpi_free(temp_divisor);
+ return rc;
+}
+
+/****************
+ * Division rounding the quotient towards -infinity.
+ * The remainder gets the same sign as the denominator.
+ * rem is optional
+ */
+
+ulong mpi_fdiv_r_ui(MPI rem, MPI dividend, ulong divisor)
+{
+ mpi_limb_t rlimb;
+
+ rlimb = mpihelp_mod_1(dividend->d, dividend->nlimbs, divisor);
+ if (rlimb && dividend->sign)
+ rlimb = divisor - rlimb;
+
+ if (rem) {
+ rem->d[0] = rlimb;
+ rem->nlimbs = rlimb ? 1 : 0;
+ }
+ return rlimb;
+}
+
+int mpi_fdiv_q(MPI quot, MPI dividend, MPI divisor)
+{
+ MPI tmp = mpi_alloc(mpi_get_nlimbs(quot));
+ if (!tmp)
+ return -ENOMEM;
+ mpi_fdiv_qr(quot, tmp, dividend, divisor);
+ mpi_free(tmp);
+ return 0;
+}
+
+int mpi_fdiv_qr(MPI quot, MPI rem, MPI dividend, MPI divisor)
+{
+ int divisor_sign = divisor->sign;
+ MPI temp_divisor = NULL;
+
+ if (quot == divisor || rem == divisor) {
+ if (mpi_copy(&temp_divisor, divisor) < 0)
+ return -ENOMEM;
+ divisor = temp_divisor;
+ }
+
+ if (mpi_tdiv_qr(quot, rem, dividend, divisor) < 0)
+ goto nomem;
+
+ if ((divisor_sign ^ dividend->sign) && rem->nlimbs) {
+ if (mpi_sub_ui(quot, quot, 1) < 0)
+ goto nomem;
+ if (mpi_add(rem, rem, divisor) < 0)
+ goto nomem;
+ }
+
+ if (temp_divisor)
+ mpi_free(temp_divisor);
+
+ return 0;
+
+nomem:
+ mpi_free(temp_divisor);
+ return -ENOMEM;
+}
+
+/* If den == quot, den needs temporary storage.
+ * If den == rem, den needs temporary storage.
+ * If num == quot, num needs temporary storage.
+ * If den has temporary storage, it can be normalized while being copied,
+ * i.e no extra storage should be allocated.
+ */
+
+int mpi_tdiv_r(MPI rem, MPI num, MPI den)
+{
+ return mpi_tdiv_qr(NULL, rem, num, den);
+}
+
+int mpi_tdiv_qr(MPI quot, MPI rem, MPI num, MPI den)
+{
+ int rc = -ENOMEM;
+ mpi_ptr_t np, dp;
+ mpi_ptr_t qp, rp;
+ mpi_size_t nsize = num->nlimbs;
+ mpi_size_t dsize = den->nlimbs;
+ mpi_size_t qsize, rsize;
+ mpi_size_t sign_remainder = num->sign;
+ mpi_size_t sign_quotient = num->sign ^ den->sign;
+ unsigned normalization_steps;
+ mpi_limb_t q_limb;
+ mpi_ptr_t marker[5];
+ int markidx = 0;
+
+ memset(marker, 0, sizeof(marker));
+
+ /* Ensure space is enough for quotient and remainder.
+ * We need space for an extra limb in the remainder, because it's
+ * up-shifted (normalized) below. */
+ rsize = nsize + 1;
+ if (mpi_resize(rem, rsize) < 0)
+ goto nomem;
+
+ qsize = rsize - dsize; /* qsize cannot be bigger than this. */
+ if (qsize <= 0) {
+ if (num != rem) {
+ rem->nlimbs = num->nlimbs;
+ rem->sign = num->sign;
+ MPN_COPY(rem->d, num->d, nsize);
+ }
+ if (quot) {
+ /* This needs to follow the assignment to rem, in case the
+ * numerator and quotient are the same. */
+ quot->nlimbs = 0;
+ quot->sign = 0;
+ }
+ return 0;
+ }
+
+ if (quot)
+ if (mpi_resize(quot, qsize) < 0)
+ goto nomem;
+
+ /* Read pointers here, when reallocation is finished. */
+ np = num->d;
+ dp = den->d;
+ rp = rem->d;
+
+ /* Optimize division by a single-limb divisor. */
+ if (dsize == 1) {
+ mpi_limb_t rlimb;
+ if (quot) {
+ qp = quot->d;
+ rlimb = mpihelp_divmod_1(qp, np, nsize, dp[0]);
+ qsize -= qp[qsize - 1] == 0;
+ quot->nlimbs = qsize;
+ quot->sign = sign_quotient;
+ } else
+ rlimb = mpihelp_mod_1(np, nsize, dp[0]);
+ rp[0] = rlimb;
+ rsize = rlimb != 0 ? 1 : 0;
+ rem->nlimbs = rsize;
+ rem->sign = sign_remainder;
+ return 0;
+ }
+
+ if (quot) {
+ qp = quot->d;
+ /* Make sure QP and NP point to different objects. Otherwise the
+ * numerator would be gradually overwritten by the quotient limbs. */
+ if (qp == np) { /* Copy NP object to temporary space. */
+ np = marker[markidx++] = mpi_alloc_limb_space(nsize);
+ MPN_COPY(np, qp, nsize);
+ }
+ } else /* Put quotient at top of remainder. */
+ qp = rp + dsize;
+
+ count_leading_zeros(normalization_steps, dp[dsize - 1]);
+
+ /* Normalize the denominator, i.e. make its most significant bit set by
+ * shifting it NORMALIZATION_STEPS bits to the left. Also shift the
+ * numerator the same number of steps (to keep the quotient the same!).
+ */
+ if (normalization_steps) {
+ mpi_ptr_t tp;
+ mpi_limb_t nlimb;
+
+ /* Shift up the denominator setting the most significant bit of
+ * the most significant word. Use temporary storage not to clobber
+ * the original contents of the denominator. */
+ tp = marker[markidx++] = mpi_alloc_limb_space(dsize);
+ if (!tp)
+ goto nomem;
+ mpihelp_lshift(tp, dp, dsize, normalization_steps);
+ dp = tp;
+
+ /* Shift up the numerator, possibly introducing a new most
+ * significant word. Move the shifted numerator in the remainder
+ * meanwhile. */
+ nlimb = mpihelp_lshift(rp, np, nsize, normalization_steps);
+ if (nlimb) {
+ rp[nsize] = nlimb;
+ rsize = nsize + 1;
+ } else
+ rsize = nsize;
+ } else {
+ /* The denominator is already normalized, as required. Copy it to
+ * temporary space if it overlaps with the quotient or remainder. */
+ if (dp == rp || (quot && (dp == qp))) {
+ mpi_ptr_t tp;
+
+ tp = marker[markidx++] = mpi_alloc_limb_space(dsize);
+ if (!tp)
+ goto nomem;
+ MPN_COPY(tp, dp, dsize);
+ dp = tp;
+ }
+
+ /* Move the numerator to the remainder. */
+ if (rp != np)
+ MPN_COPY(rp, np, nsize);
+
+ rsize = nsize;
+ }
+
+ q_limb = mpihelp_divrem(qp, 0, rp, rsize, dp, dsize);
+
+ if (quot) {
+ qsize = rsize - dsize;
+ if (q_limb) {
+ qp[qsize] = q_limb;
+ qsize += 1;
+ }
+
+ quot->nlimbs = qsize;
+ quot->sign = sign_quotient;
+ }
+
+ rsize = dsize;
+ MPN_NORMALIZE(rp, rsize);
+
+ if (normalization_steps && rsize) {
+ mpihelp_rshift(rp, rp, rsize, normalization_steps);
+ rsize -= rp[rsize - 1] == 0 ? 1 : 0;
+ }
+
+ rem->nlimbs = rsize;
+ rem->sign = sign_remainder;
+
+ rc = 0;
+nomem:
+ while (markidx)
+ mpi_free_limb_space(marker[--markidx]);
+ return rc;
+}
+
+int mpi_tdiv_q_2exp(MPI w, MPI u, unsigned count)
+{
+ mpi_size_t usize, wsize;
+ mpi_size_t limb_cnt;
+
+ usize = u->nlimbs;
+ limb_cnt = count / BITS_PER_MPI_LIMB;
+ wsize = usize - limb_cnt;
+ if (limb_cnt >= usize)
+ w->nlimbs = 0;
+ else {
+ mpi_ptr_t wp;
+ mpi_ptr_t up;
+
+ if (RESIZE_IF_NEEDED(w, wsize) < 0)
+ return -ENOMEM;
+ wp = w->d;
+ up = u->d;
+
+ count %= BITS_PER_MPI_LIMB;
+ if (count) {
+ mpihelp_rshift(wp, up + limb_cnt, wsize, count);
+ wsize -= !wp[wsize - 1];
+ } else {
+ MPN_COPY_INCR(wp, up + limb_cnt, wsize);
+ }
+
+ w->nlimbs = wsize;
+ }
+ return 0;
+}
+
+/****************
+ * Check whether dividend is divisible by divisor
+ * (note: divisor must fit into a limb)
+ */
+int mpi_divisible_ui(MPI dividend, ulong divisor)
+{
+ return !mpihelp_mod_1(dividend->d, dividend->nlimbs, divisor);
+}