lib/mpi/mpiutil.c - linux - Git at Google

 /* 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");
	/* 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");