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 | /* 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(u: 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 | |
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 |
83 | * integers of n bits - So we should change this to bits (or bytes). |
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(size: 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(objp: 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 | |
118 | if (!len) |
119 | return NULL; |
120 | |
121 | return kmalloc(size: len, GFP_KERNEL); |
122 | } |
123 | |
124 | void mpi_free_limb_space(mpi_ptr_t a) |
125 | { |
126 | if (!a) |
127 | return; |
128 | |
129 | kfree_sensitive(objp: a); |
130 | } |
131 | |
132 | void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs) |
133 | { |
134 | mpi_free_limb_space(a: 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) { |
151 | p = kcalloc(n: nlimbs, size: sizeof(mpi_limb_t), GFP_KERNEL); |
152 | if (!p) |
153 | return -ENOMEM; |
154 | memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t)); |
155 | kfree_sensitive(objp: a->d); |
156 | a->d = p; |
157 | } else { |
158 | a->d = kcalloc(n: nlimbs, size: sizeof(mpi_limb_t), GFP_KERNEL); |
159 | if (!a->d) |
160 | return -ENOMEM; |
161 | } |
162 | a->alloced = nlimbs; |
163 | return 0; |
164 | } |
165 | |
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 | |
175 | void mpi_free(MPI a) |
176 | { |
177 | if (!a) |
178 | return; |
179 | |
180 | if (a->flags & 4) |
181 | kfree_sensitive(objp: a->d); |
182 | else |
183 | mpi_free_limb_space(a: a->d); |
184 | |
185 | if (a->flags & ~7) |
186 | pr_info("invalid flag value in mpi\n" ); |
187 | kfree(objp: a); |
188 | } |
189 | EXPORT_SYMBOL_GPL(mpi_free); |
190 | |
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(a: w, ap: u->d, nlimbs: 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 |
275 | * allocating the limbs. |
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 | |
329 | MODULE_DESCRIPTION("Multiprecision maths library" ); |
330 | MODULE_LICENSE("GPL" ); |
331 | |