Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 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 | |
Tianjia Zhang | a8ea8bd | 2020-09-21 00:20:55 +0800 | [diff] [blame] | 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 | |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 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 |
Zhen Lei | 478485f | 2021-06-30 18:55:58 -0700 | [diff] [blame] | 83 | * integers of n bits - So we should change this to bits (or bytes). |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 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 | |
Dmitry Kasatkin | 4877e05 | 2012-01-26 19:13:19 +0200 | [diff] [blame] | 118 | if (!len) |
| 119 | return NULL; |
| 120 | |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 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 | |
Waiman Long | 453431a | 2020-08-06 23:18:13 -0700 | [diff] [blame] | 129 | kfree_sensitive(a); |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 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) { |
Hongbo Li | b6f7567 | 2021-08-05 16:53:32 +0800 | [diff] [blame] | 151 | p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 152 | if (!p) |
| 153 | return -ENOMEM; |
| 154 | memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t)); |
Waiman Long | 453431a | 2020-08-06 23:18:13 -0700 | [diff] [blame] | 155 | kfree_sensitive(a->d); |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 156 | a->d = p; |
| 157 | } else { |
Kees Cook | 6396bb2 | 2018-06-12 14:03:40 -0700 | [diff] [blame] | 158 | a->d = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 159 | if (!a->d) |
| 160 | return -ENOMEM; |
| 161 | } |
| 162 | a->alloced = nlimbs; |
| 163 | return 0; |
| 164 | } |
| 165 | |
Tianjia Zhang | a8ea8bd | 2020-09-21 00:20:55 +0800 | [diff] [blame] | 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 | |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 175 | void mpi_free(MPI a) |
| 176 | { |
| 177 | if (!a) |
| 178 | return; |
| 179 | |
| 180 | if (a->flags & 4) |
Waiman Long | 453431a | 2020-08-06 23:18:13 -0700 | [diff] [blame] | 181 | kfree_sensitive(a->d); |
Dmitry Kasatkin | cdec9cb | 2011-08-31 14:05:16 +0300 | [diff] [blame] | 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); |
Konstantin Khlebnikov | 4ff1582 | 2013-09-17 15:14:52 +0400 | [diff] [blame] | 190 | |
Tianjia Zhang | a8ea8bd | 2020-09-21 00:20:55 +0800 | [diff] [blame] | 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 |
Slark Xiao | cf069c3 | 2022-07-22 18:19:22 +0800 | [diff] [blame] | 275 | * allocating the limbs. |
Tianjia Zhang | a8ea8bd | 2020-09-21 00:20:55 +0800 | [diff] [blame] | 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 | |
Konstantin Khlebnikov | 4ff1582 | 2013-09-17 15:14:52 +0400 | [diff] [blame] | 329 | MODULE_DESCRIPTION("Multiprecision maths library"); |
| 330 | MODULE_LICENSE("GPL"); |