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Diffstat (limited to 'lib/mpi/mpiutil.c')
| -rw-r--r-- | lib/mpi/mpiutil.c | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/lib/mpi/mpiutil.c b/lib/mpi/mpiutil.c new file mode 100644 index 000000000..aa8c46544 --- /dev/null +++ b/lib/mpi/mpiutil.c @@ -0,0 +1,330 @@ +/* mpiutil.ac - Utility functions for MPI + * 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" + +/* Constants allocated right away at startup. */ +static MPI constants[MPI_NUMBER_OF_CONSTANTS]; + +/* Initialize the MPI subsystem. This is called early and allows to + * do some initialization without taking care of threading issues. + */ +static int __init mpi_init(void) +{ + int idx; + unsigned long value; + + for (idx = 0; idx < MPI_NUMBER_OF_CONSTANTS; idx++) { + switch (idx) { + case MPI_C_ZERO: + value = 0; + break; + case MPI_C_ONE: + value = 1; + break; + case MPI_C_TWO: + value = 2; + break; + case MPI_C_THREE: + value = 3; + break; + case MPI_C_FOUR: + value = 4; + break; + case MPI_C_EIGHT: + value = 8; + break; + default: + pr_err("MPI: invalid mpi_const selector %d\n", idx); + return -EFAULT; + } + constants[idx] = mpi_alloc_set_ui(value); + constants[idx]->flags = (16|32); + } + + return 0; +} +postcore_initcall(mpi_init); + +/* Return a constant MPI descripbed by NO which is one of the + * MPI_C_xxx macros. There is no need to copy this returned value; it + * may be used directly. + */ +MPI mpi_const(enum gcry_mpi_constants no) +{ + if ((int)no < 0 || no > MPI_NUMBER_OF_CONSTANTS) + pr_err("MPI: invalid mpi_const selector %d\n", no); + if (!constants[no]) + pr_err("MPI: MPI subsystem not initialized\n"); + return constants[no]; +} +EXPORT_SYMBOL_GPL(mpi_const); + +/**************** + * Note: It was a bad idea to use the number of limbs to allocate + * because on a alpha the limbs are large but we normally need + * integers of n bits - So we should change this to bits (or bytes). + * + * But mpi_alloc is used in a lot of places :-) + */ +MPI mpi_alloc(unsigned nlimbs) +{ + MPI a; + + a = kmalloc(sizeof *a, GFP_KERNEL); + if (!a) + return a; + + if (nlimbs) { + a->d = mpi_alloc_limb_space(nlimbs); + if (!a->d) { + kfree(a); + return NULL; + } + } else { + a->d = NULL; + } + + a->alloced = nlimbs; + a->nlimbs = 0; + a->sign = 0; + a->flags = 0; + a->nbits = 0; + return a; +} +EXPORT_SYMBOL_GPL(mpi_alloc); + +mpi_ptr_t mpi_alloc_limb_space(unsigned nlimbs) +{ + size_t len = nlimbs * sizeof(mpi_limb_t); + + if (!len) + return NULL; + + return kmalloc(len, GFP_KERNEL); +} + +void mpi_free_limb_space(mpi_ptr_t a) +{ + if (!a) + return; + + kfree_sensitive(a); +} + +void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs) +{ + mpi_free_limb_space(a->d); + a->d = ap; + a->alloced = nlimbs; +} + +/**************** + * Resize the array of A to NLIMBS. the additional space is cleared + * (set to 0) [done by m_realloc()] + */ +int mpi_resize(MPI a, unsigned nlimbs) +{ + void *p; + + if (nlimbs <= a->alloced) + return 0; /* no need to do it */ + + if (a->d) { + p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); + if (!p) + return -ENOMEM; + memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t)); + kfree_sensitive(a->d); + a->d = p; + } else { + a->d = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); + if (!a->d) + return -ENOMEM; + } + a->alloced = nlimbs; + return 0; +} + +void mpi_clear(MPI a) +{ + if (!a) + return; + a->nlimbs = 0; + a->flags = 0; +} +EXPORT_SYMBOL_GPL(mpi_clear); + +void mpi_free(MPI a) +{ + if (!a) + return; + + if (a->flags & 4) + kfree_sensitive(a->d); + else + mpi_free_limb_space(a->d); + + if (a->flags & ~7) + pr_info("invalid flag value in mpi\n"); + kfree(a); +} +EXPORT_SYMBOL_GPL(mpi_free); + +/**************** + * Note: This copy function should not interpret the MPI + * but copy it transparently. + */ +MPI mpi_copy(MPI a) +{ + int i; + MPI b; + + if (a) { + b = mpi_alloc(a->nlimbs); + b->nlimbs = a->nlimbs; + b->sign = a->sign; + b->flags = a->flags; + b->flags &= ~(16|32); /* Reset the immutable and constant flags. */ + for (i = 0; i < b->nlimbs; i++) + b->d[i] = a->d[i]; + } else + b = NULL; + return b; +} + +/**************** + * This function allocates an MPI which is optimized to hold + * a value as large as the one given in the argument and allocates it + * with the same flags as A. + */ +MPI mpi_alloc_like(MPI a) +{ + MPI b; + + if (a) { + b = mpi_alloc(a->nlimbs); + b->nlimbs = 0; + b->sign = 0; + b->flags = a->flags; + } else + b = NULL; + + return b; +} + + +/* Set U into W and release U. If W is NULL only U will be released. */ +void mpi_snatch(MPI w, MPI u) +{ + if (w) { + mpi_assign_limb_space(w, u->d, u->alloced); + w->nlimbs = u->nlimbs; + w->sign = u->sign; + w->flags = u->flags; + u->alloced = 0; + u->nlimbs = 0; + u->d = NULL; + } + mpi_free(u); +} + + +MPI mpi_set(MPI w, MPI u) +{ + mpi_ptr_t wp, up; + mpi_size_t usize = u->nlimbs; + int usign = u->sign; + + if (!w) + w = mpi_alloc(mpi_get_nlimbs(u)); + RESIZE_IF_NEEDED(w, usize); + wp = w->d; + up = u->d; + MPN_COPY(wp, up, usize); + w->nlimbs = usize; + w->flags = u->flags; + w->flags &= ~(16|32); /* Reset the immutable and constant flags. */ + w->sign = usign; + return w; +} +EXPORT_SYMBOL_GPL(mpi_set); + +MPI mpi_set_ui(MPI w, unsigned long u) +{ + if (!w) + w = mpi_alloc(1); + /* FIXME: If U is 0 we have no need to resize and thus possible + * allocating the limbs. + */ + RESIZE_IF_NEEDED(w, 1); + w->d[0] = u; + w->nlimbs = u ? 1 : 0; + w->sign = 0; + w->flags = 0; + return w; +} +EXPORT_SYMBOL_GPL(mpi_set_ui); + +MPI mpi_alloc_set_ui(unsigned long u) +{ + MPI w = mpi_alloc(1); + w->d[0] = u; + w->nlimbs = u ? 1 : 0; + w->sign = 0; + return w; +} + +/**************** + * Swap the value of A and B, when SWAP is 1. + * Leave the value when SWAP is 0. + * This implementation should be constant-time regardless of SWAP. + */ +void mpi_swap_cond(MPI a, MPI b, unsigned long swap) +{ + mpi_size_t i; + mpi_size_t nlimbs; + mpi_limb_t mask = ((mpi_limb_t)0) - swap; + mpi_limb_t x; + + if (a->alloced > b->alloced) + nlimbs = b->alloced; + else + nlimbs = a->alloced; + if (a->nlimbs > nlimbs || b->nlimbs > nlimbs) + return; + + for (i = 0; i < nlimbs; i++) { + x = mask & (a->d[i] ^ b->d[i]); + a->d[i] = a->d[i] ^ x; + b->d[i] = b->d[i] ^ x; + } + + x = mask & (a->nlimbs ^ b->nlimbs); + a->nlimbs = a->nlimbs ^ x; + b->nlimbs = b->nlimbs ^ x; + + x = mask & (a->sign ^ b->sign); + a->sign = a->sign ^ x; + b->sign = b->sign ^ x; +} + +MODULE_DESCRIPTION("Multiprecision maths library"); +MODULE_LICENSE("GPL"); |