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cdec9cb5 DK |
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 | ||
a8ea8bdd TZ |
23 | /* Constants allocated right away at startup. */ |
24 | static MPI constants[MPI_NUMBER_OF_CONSTANTS]; | |
25 | ||
26 | /* Initialize the MPI subsystem. This is called early and allows to | |
27 | * do some initialization without taking care of threading issues. | |
28 | */ | |
29 | static int __init mpi_init(void) | |
30 | { | |
31 | int idx; | |
32 | unsigned long value; | |
33 | ||
34 | for (idx = 0; idx < MPI_NUMBER_OF_CONSTANTS; idx++) { | |
35 | switch (idx) { | |
36 | case MPI_C_ZERO: | |
37 | value = 0; | |
38 | break; | |
39 | case MPI_C_ONE: | |
40 | value = 1; | |
41 | break; | |
42 | case MPI_C_TWO: | |
43 | value = 2; | |
44 | break; | |
45 | case MPI_C_THREE: | |
46 | value = 3; | |
47 | break; | |
48 | case MPI_C_FOUR: | |
49 | value = 4; | |
50 | break; | |
51 | case MPI_C_EIGHT: | |
52 | value = 8; | |
53 | break; | |
54 | default: | |
55 | pr_err("MPI: invalid mpi_const selector %d\n", idx); | |
56 | return -EFAULT; | |
57 | } | |
58 | constants[idx] = mpi_alloc_set_ui(value); | |
59 | constants[idx]->flags = (16|32); | |
60 | } | |
61 | ||
62 | return 0; | |
63 | } | |
64 | postcore_initcall(mpi_init); | |
65 | ||
66 | /* Return a constant MPI descripbed by NO which is one of the | |
67 | * MPI_C_xxx macros. There is no need to copy this returned value; it | |
68 | * may be used directly. | |
69 | */ | |
70 | MPI mpi_const(enum gcry_mpi_constants no) | |
71 | { | |
72 | if ((int)no < 0 || no > MPI_NUMBER_OF_CONSTANTS) | |
73 | pr_err("MPI: invalid mpi_const selector %d\n", no); | |
74 | if (!constants[no]) | |
75 | pr_err("MPI: MPI subsystem not initialized\n"); | |
76 | return constants[no]; | |
77 | } | |
78 | EXPORT_SYMBOL_GPL(mpi_const); | |
79 | ||
cdec9cb5 DK |
80 | /**************** |
81 | * Note: It was a bad idea to use the number of limbs to allocate | |
82 | * because on a alpha the limbs are large but we normally need | |
478485f6 | 83 | * integers of n bits - So we should change this to bits (or bytes). |
cdec9cb5 DK |
84 | * |
85 | * But mpi_alloc is used in a lot of places :-) | |
86 | */ | |
87 | MPI mpi_alloc(unsigned nlimbs) | |
88 | { | |
89 | MPI a; | |
90 | ||
91 | a = kmalloc(sizeof *a, GFP_KERNEL); | |
92 | if (!a) | |
93 | return a; | |
94 | ||
95 | if (nlimbs) { | |
96 | a->d = mpi_alloc_limb_space(nlimbs); | |
97 | if (!a->d) { | |
98 | kfree(a); | |
99 | return NULL; | |
100 | } | |
101 | } else { | |
102 | a->d = NULL; | |
103 | } | |
104 | ||
105 | a->alloced = nlimbs; | |
106 | a->nlimbs = 0; | |
107 | a->sign = 0; | |
108 | a->flags = 0; | |
109 | a->nbits = 0; | |
110 | return a; | |
111 | } | |
112 | EXPORT_SYMBOL_GPL(mpi_alloc); | |
113 | ||
114 | mpi_ptr_t mpi_alloc_limb_space(unsigned nlimbs) | |
115 | { | |
116 | size_t len = nlimbs * sizeof(mpi_limb_t); | |
117 | ||
4877e056 DK |
118 | if (!len) |
119 | return NULL; | |
120 | ||
cdec9cb5 DK |
121 | return kmalloc(len, GFP_KERNEL); |
122 | } | |
123 | ||
124 | void mpi_free_limb_space(mpi_ptr_t a) | |
125 | { | |
126 | if (!a) | |
127 | return; | |
128 | ||
453431a5 | 129 | kfree_sensitive(a); |
cdec9cb5 DK |
130 | } |
131 | ||
132 | void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs) | |
133 | { | |
134 | mpi_free_limb_space(a->d); | |
135 | a->d = ap; | |
136 | a->alloced = nlimbs; | |
137 | } | |
138 | ||
139 | /**************** | |
140 | * Resize the array of A to NLIMBS. the additional space is cleared | |
141 | * (set to 0) [done by m_realloc()] | |
142 | */ | |
143 | int mpi_resize(MPI a, unsigned nlimbs) | |
144 | { | |
145 | void *p; | |
146 | ||
147 | if (nlimbs <= a->alloced) | |
148 | return 0; /* no need to do it */ | |
149 | ||
150 | if (a->d) { | |
b6f75672 | 151 | p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); |
cdec9cb5 DK |
152 | if (!p) |
153 | return -ENOMEM; | |
154 | memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t)); | |
453431a5 | 155 | kfree_sensitive(a->d); |
cdec9cb5 DK |
156 | a->d = p; |
157 | } else { | |
6396bb22 | 158 | a->d = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); |
cdec9cb5 DK |
159 | if (!a->d) |
160 | return -ENOMEM; | |
161 | } | |
162 | a->alloced = nlimbs; | |
163 | return 0; | |
164 | } | |
165 | ||
a8ea8bdd TZ |
166 | void mpi_clear(MPI a) |
167 | { | |
168 | if (!a) | |
169 | return; | |
170 | a->nlimbs = 0; | |
171 | a->flags = 0; | |
172 | } | |
173 | EXPORT_SYMBOL_GPL(mpi_clear); | |
174 | ||
cdec9cb5 DK |
175 | void mpi_free(MPI a) |
176 | { | |
177 | if (!a) | |
178 | return; | |
179 | ||
180 | if (a->flags & 4) | |
453431a5 | 181 | kfree_sensitive(a->d); |
cdec9cb5 DK |
182 | else |
183 | mpi_free_limb_space(a->d); | |
184 | ||
185 | if (a->flags & ~7) | |
186 | pr_info("invalid flag value in mpi\n"); | |
187 | kfree(a); | |
188 | } | |
189 | EXPORT_SYMBOL_GPL(mpi_free); | |
4ff15822 | 190 | |
a8ea8bdd TZ |
191 | /**************** |
192 | * Note: This copy function should not interpret the MPI | |
193 | * but copy it transparently. | |
194 | */ | |
195 | MPI mpi_copy(MPI a) | |
196 | { | |
197 | int i; | |
198 | MPI b; | |
199 | ||
200 | if (a) { | |
201 | b = mpi_alloc(a->nlimbs); | |
202 | b->nlimbs = a->nlimbs; | |
203 | b->sign = a->sign; | |
204 | b->flags = a->flags; | |
205 | b->flags &= ~(16|32); /* Reset the immutable and constant flags. */ | |
206 | for (i = 0; i < b->nlimbs; i++) | |
207 | b->d[i] = a->d[i]; | |
208 | } else | |
209 | b = NULL; | |
210 | return b; | |
211 | } | |
212 | ||
213 | /**************** | |
214 | * This function allocates an MPI which is optimized to hold | |
215 | * a value as large as the one given in the argument and allocates it | |
216 | * with the same flags as A. | |
217 | */ | |
218 | MPI mpi_alloc_like(MPI a) | |
219 | { | |
220 | MPI b; | |
221 | ||
222 | if (a) { | |
223 | b = mpi_alloc(a->nlimbs); | |
224 | b->nlimbs = 0; | |
225 | b->sign = 0; | |
226 | b->flags = a->flags; | |
227 | } else | |
228 | b = NULL; | |
229 | ||
230 | return b; | |
231 | } | |
232 | ||
233 | ||
234 | /* Set U into W and release U. If W is NULL only U will be released. */ | |
235 | void mpi_snatch(MPI w, MPI u) | |
236 | { | |
237 | if (w) { | |
238 | mpi_assign_limb_space(w, u->d, u->alloced); | |
239 | w->nlimbs = u->nlimbs; | |
240 | w->sign = u->sign; | |
241 | w->flags = u->flags; | |
242 | u->alloced = 0; | |
243 | u->nlimbs = 0; | |
244 | u->d = NULL; | |
245 | } | |
246 | mpi_free(u); | |
247 | } | |
248 | ||
249 | ||
250 | MPI mpi_set(MPI w, MPI u) | |
251 | { | |
252 | mpi_ptr_t wp, up; | |
253 | mpi_size_t usize = u->nlimbs; | |
254 | int usign = u->sign; | |
255 | ||
256 | if (!w) | |
257 | w = mpi_alloc(mpi_get_nlimbs(u)); | |
258 | RESIZE_IF_NEEDED(w, usize); | |
259 | wp = w->d; | |
260 | up = u->d; | |
261 | MPN_COPY(wp, up, usize); | |
262 | w->nlimbs = usize; | |
263 | w->flags = u->flags; | |
264 | w->flags &= ~(16|32); /* Reset the immutable and constant flags. */ | |
265 | w->sign = usign; | |
266 | return w; | |
267 | } | |
268 | EXPORT_SYMBOL_GPL(mpi_set); | |
269 | ||
270 | MPI mpi_set_ui(MPI w, unsigned long u) | |
271 | { | |
272 | if (!w) | |
273 | w = mpi_alloc(1); | |
274 | /* FIXME: If U is 0 we have no need to resize and thus possible | |
cf069c3b | 275 | * allocating the limbs. |
a8ea8bdd TZ |
276 | */ |
277 | RESIZE_IF_NEEDED(w, 1); | |
278 | w->d[0] = u; | |
279 | w->nlimbs = u ? 1 : 0; | |
280 | w->sign = 0; | |
281 | w->flags = 0; | |
282 | return w; | |
283 | } | |
284 | EXPORT_SYMBOL_GPL(mpi_set_ui); | |
285 | ||
286 | MPI mpi_alloc_set_ui(unsigned long u) | |
287 | { | |
288 | MPI w = mpi_alloc(1); | |
289 | w->d[0] = u; | |
290 | w->nlimbs = u ? 1 : 0; | |
291 | w->sign = 0; | |
292 | return w; | |
293 | } | |
294 | ||
295 | /**************** | |
296 | * Swap the value of A and B, when SWAP is 1. | |
297 | * Leave the value when SWAP is 0. | |
298 | * This implementation should be constant-time regardless of SWAP. | |
299 | */ | |
300 | void mpi_swap_cond(MPI a, MPI b, unsigned long swap) | |
301 | { | |
302 | mpi_size_t i; | |
303 | mpi_size_t nlimbs; | |
304 | mpi_limb_t mask = ((mpi_limb_t)0) - swap; | |
305 | mpi_limb_t x; | |
306 | ||
307 | if (a->alloced > b->alloced) | |
308 | nlimbs = b->alloced; | |
309 | else | |
310 | nlimbs = a->alloced; | |
311 | if (a->nlimbs > nlimbs || b->nlimbs > nlimbs) | |
312 | return; | |
313 | ||
314 | for (i = 0; i < nlimbs; i++) { | |
315 | x = mask & (a->d[i] ^ b->d[i]); | |
316 | a->d[i] = a->d[i] ^ x; | |
317 | b->d[i] = b->d[i] ^ x; | |
318 | } | |
319 | ||
320 | x = mask & (a->nlimbs ^ b->nlimbs); | |
321 | a->nlimbs = a->nlimbs ^ x; | |
322 | b->nlimbs = b->nlimbs ^ x; | |
323 | ||
324 | x = mask & (a->sign ^ b->sign); | |
325 | a->sign = a->sign ^ x; | |
326 | b->sign = b->sign ^ x; | |
327 | } | |
328 | ||
4ff15822 KK |
329 | MODULE_DESCRIPTION("Multiprecision maths library"); |
330 | MODULE_LICENSE("GPL"); |