1 files changed, 527 insertions, 0 deletions

diff --git a/lib/mpi/mpih-mul.c b/lib/mpi/mpih-mul.c
new file mode 100644
index 000000000000..c69c5eef233b
--- /dev/null
+++ b/lib/mpi/mpih-mul.c
@@ -0,0 +1,527 @@
+/* mpihelp-mul.c  -  MPI helper functions
+ * Copyright (C) 1994, 1996, 1998, 1999,
+ *               2000 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"
+
+#define MPN_MUL_N_RECURSE(prodp, up, vp, size, tspace)          \
+        do {                                                    \
+                if ((size) < KARATSUBA_THRESHOLD)               \
+                        mul_n_basecase(prodp, up, vp, size);    \
+                else                                            \
+                        mul_n(prodp, up, vp, size, tspace);     \
+        } while (0);
+
+#define MPN_SQR_N_RECURSE(prodp, up, size, tspace)              \
+        do {                                                    \
+                if ((size) < KARATSUBA_THRESHOLD)               \
+                        mpih_sqr_n_basecase(prodp, up, size);   \
+                else                                            \
+                        mpih_sqr_n(prodp, up, size, tspace);    \
+        } while (0);
+
+/* Multiply the natural numbers u (pointed to by UP) and v (pointed to by VP),
+ * both with SIZE limbs, and store the result at PRODP.  2 * SIZE limbs are
+ * always stored.  Return the most significant limb.
+ *
+ * Argument constraints:
+ * 1. PRODP != UP and PRODP != VP, i.e. the destination
+ *    must be distinct from the multiplier and the multiplicand.
+ *
+ *
+ * Handle simple cases with traditional multiplication.
+ *
+ * This is the most critical code of multiplication.  All multiplies rely
+ * on this, both small and huge.  Small ones arrive here immediately.  Huge
+ * ones arrive here as this is the base case for Karatsuba's recursive
+ * algorithm below.
+ */
+
+static mpi_limb_t
+mul_n_basecase(mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp, mpi_size_t size)
+{
+        mpi_size_t i;
+        mpi_limb_t cy;
+        mpi_limb_t v_limb;
+
+        /* Multiply by the first limb in V separately, as the result can be
+         * stored (not added) to PROD.  We also avoid a loop for zeroing.  */
+        v_limb = vp[0];
+        if (v_limb <= 1) {
+                if (v_limb == 1)
+                        MPN_COPY(prodp, up, size);
+                else
+                        MPN_ZERO(prodp, size);
+                cy = 0;
+        } else
+                cy = mpihelp_mul_1(prodp, up, size, v_limb);
+
+        prodp[size] = cy;
+        prodp++;
+
+        /* For each iteration in the outer loop, multiply one limb from
+         * U with one limb from V, and add it to PROD.  */
+        for (i = 1; i < size; i++) {
+                v_limb = vp[i];
+                if (v_limb <= 1) {
+                        cy = 0;
+                        if (v_limb == 1)
+                                cy = mpihelp_add_n(prodp, prodp, up, size);
+                } else
+                        cy = mpihelp_addmul_1(prodp, up, size, v_limb);
+
+                prodp[size] = cy;
+                prodp++;
+        }
+
+        return cy;
+}
+
+static void
+mul_n(mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp,
+                mpi_size_t size, mpi_ptr_t tspace)
+{
+        if (size & 1) {
+                /* The size is odd, and the code below doesn't handle that.
+                 * Multiply the least significant (size - 1) limbs with a recursive
+                 * call, and handle the most significant limb of S1 and S2
+                 * separately.
+                 * A slightly faster way to do this would be to make the Karatsuba
+                 * code below behave as if the size were even, and let it check for
+                 * odd size in the end.  I.e., in essence move this code to the end.
+                 * Doing so would save us a recursive call, and potentially make the
+                 * stack grow a lot less.
+                 */
+                mpi_size_t esize = size - 1;    /* even size */
+                mpi_limb_t cy_limb;
+
+                MPN_MUL_N_RECURSE(prodp, up, vp, esize, tspace);
+                cy_limb = mpihelp_addmul_1(prodp + esize, up, esize, vp[esize]);
+                prodp[esize + esize] = cy_limb;
+                cy_limb = mpihelp_addmul_1(prodp + esize, vp, size, up[esize]);
+                prodp[esize + size] = cy_limb;
+        } else {
+                /* Anatolij Alekseevich Karatsuba's divide-and-conquer algorithm.
+                 *
+                 * Split U in two pieces, U1 and U0, such that
+                 * U = U0 + U1*(B**n),
+                 * and V in V1 and V0, such that
+                 * V = V0 + V1*(B**n).
+                 *
+                 * UV is then computed recursively using the identity
+                 *
+                 *        2n   n          n                     n
+                 * UV = (B  + B )U V  +  B (U -U )(V -V )  +  (B + 1)U V
+                 *                1 1        1  0   0  1              0 0
+                 *
+                 * Where B = 2**BITS_PER_MP_LIMB.
+                 */
+                mpi_size_t hsize = size >> 1;
+                mpi_limb_t cy;
+                int negflg;
+
+                /* Product H.      ________________  ________________
+                 *                |_____U1 x V1____||____U0 x V0_____|
+                 * Put result in upper part of PROD and pass low part of TSPACE
+                 * as new TSPACE.
+                 */
+                MPN_MUL_N_RECURSE(prodp + size, up + hsize, vp + hsize, hsize,
+                                  tspace);
+
+                /* Product M.      ________________
+                 *                |_(U1-U0)(V0-V1)_|
+                 */
+                if (mpihelp_cmp(up + hsize, up, hsize) >= 0) {
+                        mpihelp_sub_n(prodp, up + hsize, up, hsize);
+                        negflg = 0;
+                } else {
+                        mpihelp_sub_n(prodp, up, up + hsize, hsize);
+                        negflg = 1;
+                }
+                if (mpihelp_cmp(vp + hsize, vp, hsize) >= 0) {
+                        mpihelp_sub_n(prodp + hsize, vp + hsize, vp, hsize);
+                        negflg ^= 1;
+                } else {
+                        mpihelp_sub_n(prodp + hsize, vp, vp + hsize, hsize);
+                        /* No change of NEGFLG.  */
+                }
+                /* Read temporary operands from low part of PROD.
+                 * Put result in low part of TSPACE using upper part of TSPACE
+                 * as new TSPACE.
+                 */
+                MPN_MUL_N_RECURSE(tspace, prodp, prodp + hsize, hsize,
+                                  tspace + size);
+
+                /* Add/copy product H. */
+                MPN_COPY(prodp + hsize, prodp + size, hsize);
+                cy = mpihelp_add_n(prodp + size, prodp + size,
+                                   prodp + size + hsize, hsize);
+
+                /* Add product M (if NEGFLG M is a negative number) */
+                if (negflg)
+                        cy -=
+                            mpihelp_sub_n(prodp + hsize, prodp + hsize, tspace,
+                                          size);
+                else
+                        cy +=
+                            mpihelp_add_n(prodp + hsize, prodp + hsize, tspace,
+                                          size);
+
+                /* Product L.      ________________  ________________
+                 *                |________________||____U0 x V0_____|
+                 * Read temporary operands from low part of PROD.
+                 * Put result in low part of TSPACE using upper part of TSPACE
+                 * as new TSPACE.
+                 */
+                MPN_MUL_N_RECURSE(tspace, up, vp, hsize, tspace + size);
+
+                /* Add/copy Product L (twice) */
+
+                cy += mpihelp_add_n(prodp + hsize, prodp + hsize, tspace, size);
+                if (cy)
+                        mpihelp_add_1(prodp + hsize + size,
+                                      prodp + hsize + size, hsize, cy);
+
+                MPN_COPY(prodp, tspace, hsize);
+                cy = mpihelp_add_n(prodp + hsize, prodp + hsize, tspace + hsize,
+                                   hsize);
+                if (cy)
+                        mpihelp_add_1(prodp + size, prodp + size, size, 1);
+        }
+}
+
+void mpih_sqr_n_basecase(mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t size)
+{
+        mpi_size_t i;
+        mpi_limb_t cy_limb;
+        mpi_limb_t v_limb;
+
+        /* Multiply by the first limb in V separately, as the result can be
+         * stored (not added) to PROD.  We also avoid a loop for zeroing.  */
+        v_limb = up[0];
+        if (v_limb <= 1) {
+                if (v_limb == 1)
+                        MPN_COPY(prodp, up, size);
+                else
+                        MPN_ZERO(prodp, size);
+                cy_limb = 0;
+        } else
+                cy_limb = mpihelp_mul_1(prodp, up, size, v_limb);
+
+        prodp[size] = cy_limb;
+        prodp++;
+
+        /* For each iteration in the outer loop, multiply one limb from
+         * U with one limb from V, and add it to PROD.  */
+        for (i = 1; i < size; i++) {
+                v_limb = up[i];
+                if (v_limb <= 1) {
+                        cy_limb = 0;
+                        if (v_limb == 1)
+                                cy_limb = mpihelp_add_n(prodp, prodp, up, size);
+                } else
+                        cy_limb = mpihelp_addmul_1(prodp, up, size, v_limb);
+
+                prodp[size] = cy_limb;
+                prodp++;
+        }
+}
+
+void
+mpih_sqr_n(mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t size, mpi_ptr_t tspace)
+{
+        if (size & 1) {
+                /* The size is odd, and the code below doesn't handle that.
+                 * Multiply the least significant (size - 1) limbs with a recursive
+                 * call, and handle the most significant limb of S1 and S2
+                 * separately.
+                 * A slightly faster way to do this would be to make the Karatsuba
+                 * code below behave as if the size were even, and let it check for
+                 * odd size in the end.  I.e., in essence move this code to the end.
+                 * Doing so would save us a recursive call, and potentially make the
+                 * stack grow a lot less.
+                 */
+                mpi_size_t esize = size - 1;    /* even size */
+                mpi_limb_t cy_limb;
+
+                MPN_SQR_N_RECURSE(prodp, up, esize, tspace);
+                cy_limb = mpihelp_addmul_1(prodp + esize, up, esize, up[esize]);
+                prodp[esize + esize] = cy_limb;
+                cy_limb = mpihelp_addmul_1(prodp + esize, up, size, up[esize]);
+
+                prodp[esize + size] = cy_limb;
+        } else {
+                mpi_size_t hsize = size >> 1;
+                mpi_limb_t cy;
+
+                /* Product H.      ________________  ________________
+                 *                |_____U1 x U1____||____U0 x U0_____|
+                 * Put result in upper part of PROD and pass low part of TSPACE
+                 * as new TSPACE.
+                 */
+                MPN_SQR_N_RECURSE(prodp + size, up + hsize, hsize, tspace);
+
+                /* Product M.      ________________
+                 *                |_(U1-U0)(U0-U1)_|
+                 */
+                if (mpihelp_cmp(up + hsize, up, hsize) >= 0)
+                        mpihelp_sub_n(prodp, up + hsize, up, hsize);
+                else
+                        mpihelp_sub_n(prodp, up, up + hsize, hsize);
+
+                /* Read temporary operands from low part of PROD.
+                 * Put result in low part of TSPACE using upper part of TSPACE
+                 * as new TSPACE.  */
+                MPN_SQR_N_RECURSE(tspace, prodp, hsize, tspace + size);
+
+                /* Add/copy product H  */
+                MPN_COPY(prodp + hsize, prodp + size, hsize);
+                cy = mpihelp_add_n(prodp + size, prodp + size,
+                                   prodp + size + hsize, hsize);
+
+                /* Add product M (if NEGFLG M is a negative number).  */
+                cy -= mpihelp_sub_n(prodp + hsize, prodp + hsize, tspace, size);
+
+                /* Product L.      ________________  ________________
+                 *                |________________||____U0 x U0_____|
+                 * Read temporary operands from low part of PROD.
+                 * Put result in low part of TSPACE using upper part of TSPACE
+                 * as new TSPACE.  */
+                MPN_SQR_N_RECURSE(tspace, up, hsize, tspace + size);
+
+                /* Add/copy Product L (twice).  */
+                cy += mpihelp_add_n(prodp + hsize, prodp + hsize, tspace, size);
+                if (cy)
+                        mpihelp_add_1(prodp + hsize + size,
+                                      prodp + hsize + size, hsize, cy);
+
+                MPN_COPY(prodp, tspace, hsize);
+                cy = mpihelp_add_n(prodp + hsize, prodp + hsize, tspace + hsize,
+                                   hsize);
+                if (cy)
+                        mpihelp_add_1(prodp + size, prodp + size, size, 1);
+        }
+}
+
+/* This should be made into an inline function in gmp.h.  */
+int mpihelp_mul_n(mpi_ptr_t prodp, mpi_ptr_t up, mpi_ptr_t vp, mpi_size_t size)
+{
+        if (up == vp) {
+                if (size < KARATSUBA_THRESHOLD)
+                        mpih_sqr_n_basecase(prodp, up, size);
+                else {
+                        mpi_ptr_t tspace;
+                        tspace = mpi_alloc_limb_space(2 * size);
+                        if (!tspace)
+                                return -ENOMEM;
+                        mpih_sqr_n(prodp, up, size, tspace);
+                        mpi_free_limb_space(tspace);
+                }
+        } else {
+                if (size < KARATSUBA_THRESHOLD)
+                        mul_n_basecase(prodp, up, vp, size);
+                else {
+                        mpi_ptr_t tspace;
+                        tspace = mpi_alloc_limb_space(2 * size);
+                        if (!tspace)
+                                return -ENOMEM;
+                        mul_n(prodp, up, vp, size, tspace);
+                        mpi_free_limb_space(tspace);
+                }
+        }
+
+        return 0;
+}
+
+int
+mpihelp_mul_karatsuba_case(mpi_ptr_t prodp,
+                           mpi_ptr_t up, mpi_size_t usize,
+                           mpi_ptr_t vp, mpi_size_t vsize,
+                           struct karatsuba_ctx *ctx)
+{
+        mpi_limb_t cy;
+
+        if (!ctx->tspace || ctx->tspace_size < vsize) {
+                if (ctx->tspace)
+                        mpi_free_limb_space(ctx->tspace);
+                ctx->tspace = mpi_alloc_limb_space(2 * vsize);
+                if (!ctx->tspace)
+                        return -ENOMEM;
+                ctx->tspace_size = vsize;
+        }
+
+        MPN_MUL_N_RECURSE(prodp, up, vp, vsize, ctx->tspace);
+
+        prodp += vsize;
+        up += vsize;
+        usize -= vsize;
+        if (usize >= vsize) {
+                if (!ctx->tp || ctx->tp_size < vsize) {
+                        if (ctx->tp)
+                                mpi_free_limb_space(ctx->tp);
+                        ctx->tp = mpi_alloc_limb_space(2 * vsize);
+                        if (!ctx->tp) {
+                                if (ctx->tspace)
+                                        mpi_free_limb_space(ctx->tspace);
+                                ctx->tspace = NULL;
+                                return -ENOMEM;
+                        }
+                        ctx->tp_size = vsize;
+                }
+
+                do {
+                        MPN_MUL_N_RECURSE(ctx->tp, up, vp, vsize, ctx->tspace);
+                        cy = mpihelp_add_n(prodp, prodp, ctx->tp, vsize);
+                        mpihelp_add_1(prodp + vsize, ctx->tp + vsize, vsize,
+                                      cy);
+                        prodp += vsize;
+                        up += vsize;
+                        usize -= vsize;
+                } while (usize >= vsize);
+        }
+
+        if (usize) {
+                if (usize < KARATSUBA_THRESHOLD) {
+                        mpi_limb_t tmp;
+                        if (mpihelp_mul(ctx->tspace, vp, vsize, up, usize, &tmp)
+                            < 0)
+                                return -ENOMEM;
+                } else {
+                        if (!ctx->next) {
+                                ctx->next = kzalloc(sizeof *ctx, GFP_KERNEL);
+                                if (!ctx->next)
+                                        return -ENOMEM;
+                        }
+                        if (mpihelp_mul_karatsuba_case(ctx->tspace,
+                                                       vp, vsize,
+                                                       up, usize,
+                                                       ctx->next) < 0)
+                                return -ENOMEM;
+                }
+
+                cy = mpihelp_add_n(prodp, prodp, ctx->tspace, vsize);
+                mpihelp_add_1(prodp + vsize, ctx->tspace + vsize, usize, cy);
+        }
+
+        return 0;
+}
+
+void mpihelp_release_karatsuba_ctx(struct karatsuba_ctx *ctx)
+{
+        struct karatsuba_ctx *ctx2;
+
+        if (ctx->tp)
+                mpi_free_limb_space(ctx->tp);
+        if (ctx->tspace)
+                mpi_free_limb_space(ctx->tspace);
+        for (ctx = ctx->next; ctx; ctx = ctx2) {
+                ctx2 = ctx->next;
+                if (ctx->tp)
+                        mpi_free_limb_space(ctx->tp);
+                if (ctx->tspace)
+                        mpi_free_limb_space(ctx->tspace);
+                kfree(ctx);
+        }
+}
+
+/* Multiply the natural numbers u (pointed to by UP, with USIZE limbs)
+ * and v (pointed to by VP, with VSIZE limbs), and store the result at
+ * PRODP.  USIZE + VSIZE limbs are always stored, but if the input
+ * operands are normalized.  Return the most significant limb of the
+ * result.
+ *
+ * NOTE: The space pointed to by PRODP is overwritten before finished
+ * with U and V, so overlap is an error.
+ *
+ * Argument constraints:
+ * 1. USIZE >= VSIZE.
+ * 2. PRODP != UP and PRODP != VP, i.e. the destination
+ *    must be distinct from the multiplier and the multiplicand.
+ */
+
+int
+mpihelp_mul(mpi_ptr_t prodp, mpi_ptr_t up, mpi_size_t usize,
+            mpi_ptr_t vp, mpi_size_t vsize, mpi_limb_t *_result)
+{
+        mpi_ptr_t prod_endp = prodp + usize + vsize - 1;
+        mpi_limb_t cy;
+        struct karatsuba_ctx ctx;
+
+        if (vsize < KARATSUBA_THRESHOLD) {
+                mpi_size_t i;
+                mpi_limb_t v_limb;
+
+                if (!vsize) {
+                        *_result = 0;
+                        return 0;
+                }
+
+                /* Multiply by the first limb in V separately, as the result can be
+                 * stored (not added) to PROD.  We also avoid a loop for zeroing.  */
+                v_limb = vp[0];
+                if (v_limb <= 1) {
+                        if (v_limb == 1)
+                                MPN_COPY(prodp, up, usize);
+                        else
+                                MPN_ZERO(prodp, usize);
+                        cy = 0;
+                } else
+                        cy = mpihelp_mul_1(prodp, up, usize, v_limb);
+
+                prodp[usize] = cy;
+                prodp++;
+
+                /* For each iteration in the outer loop, multiply one limb from
+                 * U with one limb from V, and add it to PROD.  */
+                for (i = 1; i < vsize; i++) {
+                        v_limb = vp[i];
+                        if (v_limb <= 1) {
+                                cy = 0;
+                                if (v_limb == 1)
+                                        cy = mpihelp_add_n(prodp, prodp, up,
+                                                           usize);
+                        } else
+                                cy = mpihelp_addmul_1(prodp, up, usize, v_limb);
+
+                        prodp[usize] = cy;
+                        prodp++;
+                }
+
+                *_result = cy;
+                return 0;
+        }
+
+        memset(&ctx, 0, sizeof ctx);
+        if (mpihelp_mul_karatsuba_case(prodp, up, usize, vp, vsize, &ctx) < 0)
+                return -ENOMEM;
+        mpihelp_release_karatsuba_ctx(&ctx);
+        *_result = *prod_endp;
+        return 0;
+}