https://github.com/torvalds/linux
Tip revision: 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 authored by Linus Torvalds on 25 January 2021, 00:47:14 UTC
Linux 5.11-rc5
Linux 5.11-rc5
Tip revision: 6ee1d74
mpiutil.c
/* 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 chnage 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 = kmalloc_array(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 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");