xref: /linux/lib/crypto/mpi/mpiutil.c (revision 85ffc6e4ed3712f8b3fedb3fbe42afae644a699c)
1 /* mpiutil.ac  -  Utility functions for MPI
2  * Copyright (C) 1998, 1999 Free Software Foundation, Inc.
3  *
4  * This file is part of GnuPG.
5  *
6  * GnuPG is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * GnuPG is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
19  */
20 
21 #include "mpi-internal.h"
22 
23 /****************
24  * Note:  It was a bad idea to use the number of limbs to allocate
25  *	  because on a alpha the limbs are large but we normally need
26  *	  integers of n bits - So we should change this to bits (or bytes).
27  *
28  *	  But mpi_alloc is used in a lot of places :-)
29  */
mpi_alloc(unsigned nlimbs)30 MPI mpi_alloc(unsigned nlimbs)
31 {
32 	MPI a;
33 
34 	a = kmalloc(sizeof *a, GFP_KERNEL);
35 	if (!a)
36 		return a;
37 
38 	if (nlimbs) {
39 		a->d = mpi_alloc_limb_space(nlimbs);
40 		if (!a->d) {
41 			kfree(a);
42 			return NULL;
43 		}
44 	} else {
45 		a->d = NULL;
46 	}
47 
48 	a->alloced = nlimbs;
49 	a->nlimbs = 0;
50 	a->sign = 0;
51 	a->flags = 0;
52 	a->nbits = 0;
53 	return a;
54 }
55 EXPORT_SYMBOL_GPL(mpi_alloc);
56 
mpi_alloc_limb_space(unsigned nlimbs)57 mpi_ptr_t mpi_alloc_limb_space(unsigned nlimbs)
58 {
59 	size_t len = nlimbs * sizeof(mpi_limb_t);
60 
61 	if (!len)
62 		return NULL;
63 
64 	return kmalloc(len, GFP_KERNEL);
65 }
66 
mpi_free_limb_space(mpi_ptr_t a)67 void mpi_free_limb_space(mpi_ptr_t a)
68 {
69 	if (!a)
70 		return;
71 
72 	kfree_sensitive(a);
73 }
74 
mpi_assign_limb_space(MPI a,mpi_ptr_t ap,unsigned nlimbs)75 void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs)
76 {
77 	mpi_free_limb_space(a->d);
78 	a->d = ap;
79 	a->alloced = nlimbs;
80 }
81 
82 /****************
83  * Resize the array of A to NLIMBS. the additional space is cleared
84  * (set to 0) [done by m_realloc()]
85  */
mpi_resize(MPI a,unsigned nlimbs)86 int mpi_resize(MPI a, unsigned nlimbs)
87 {
88 	void *p;
89 
90 	if (nlimbs <= a->alloced)
91 		return 0;	/* no need to do it */
92 
93 	if (a->d) {
94 		p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL);
95 		if (!p)
96 			return -ENOMEM;
97 		memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t));
98 		kfree_sensitive(a->d);
99 		a->d = p;
100 	} else {
101 		a->d = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL);
102 		if (!a->d)
103 			return -ENOMEM;
104 	}
105 	a->alloced = nlimbs;
106 	return 0;
107 }
108 
mpi_free(MPI a)109 void mpi_free(MPI a)
110 {
111 	if (!a)
112 		return;
113 
114 	if (a->flags & 4)
115 		kfree_sensitive(a->d);
116 	else
117 		mpi_free_limb_space(a->d);
118 
119 	if (a->flags & ~7)
120 		pr_info("invalid flag value in mpi\n");
121 	kfree(a);
122 }
123 EXPORT_SYMBOL_GPL(mpi_free);
124 
125 /****************
126  * Note: This copy function should not interpret the MPI
127  *	 but copy it transparently.
128  */
mpi_copy(MPI a)129 MPI mpi_copy(MPI a)
130 {
131 	int i;
132 	MPI b;
133 
134 	if (a) {
135 		b = mpi_alloc(a->nlimbs);
136 		if (!b)
137 			return NULL;
138 		b->nlimbs = a->nlimbs;
139 		b->sign = a->sign;
140 		b->flags = a->flags;
141 		b->flags &= ~(16|32); /* Reset the immutable and constant flags. */
142 		for (i = 0; i < b->nlimbs; i++)
143 			b->d[i] = a->d[i];
144 	} else
145 		b = NULL;
146 	return b;
147 }
148 
149 MODULE_DESCRIPTION("Multiprecision maths library");
150 MODULE_LICENSE("GPL");
151