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annotate libtommath/bn_mp_pack.c @ 1861:2b3a8026a6ce

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Add re-exec for server This allows ASLR to re-randomize the address space for every connection, preventing some vulnerabilities from being exploitable by repeated probing. Overhead (memory and time) is yet to be confirmed. At present this is only enabled on Linux. Other BSD platforms with fexecve() would probably also work though have not been tested.
author Matt Johnston <matt@ucc.asn.au>
date Sun, 30 Jan 2022 10:14:56 +0800
parents 1051e4eea25a
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1692
1051e4eea25a Update LibTomMath to 1.2.0 (#84)
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1 #include "tommath_private.h"
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2 #ifdef BN_MP_PACK_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
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4 /* SPDX-License-Identifier: Unlicense */
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5
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6 /* based on gmp's mpz_export.
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7 * see http://gmplib.org/manual/Integer-Import-and-Export.html
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8 */
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9 mp_err mp_pack(void *rop, size_t maxcount, size_t *written, mp_order order, size_t size,
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10 mp_endian endian, size_t nails, const mp_int *op)
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11 {
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12 mp_err err;
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13 size_t odd_nails, nail_bytes, i, j, count;
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14 unsigned char odd_nail_mask;
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15
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16 mp_int t;
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17
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18 count = mp_pack_count(op, nails, size);
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19
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20 if (count > maxcount) {
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21 return MP_BUF;
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22 }
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23
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24 if ((err = mp_init_copy(&t, op)) != MP_OKAY) {
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25 return err;
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26 }
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27
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28 if (endian == MP_NATIVE_ENDIAN) {
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29 MP_GET_ENDIANNESS(endian);
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30 }
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31
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32 odd_nails = (nails % 8u);
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33 odd_nail_mask = 0xff;
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34 for (i = 0u; i < odd_nails; ++i) {
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35 odd_nail_mask ^= (unsigned char)(1u << (7u - i));
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36 }
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37 nail_bytes = nails / 8u;
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38
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39 for (i = 0u; i < count; ++i) {
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40 for (j = 0u; j < size; ++j) {
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41 unsigned char *byte = (unsigned char *)rop +
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42 (((order == MP_LSB_FIRST) ? i : ((count - 1u) - i)) * size) +
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43 ((endian == MP_LITTLE_ENDIAN) ? j : ((size - 1u) - j));
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44
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45 if (j >= (size - nail_bytes)) {
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46 *byte = 0;
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47 continue;
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48 }
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49
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50 *byte = (unsigned char)((j == ((size - nail_bytes) - 1u)) ? (t.dp[0] & odd_nail_mask) : (t.dp[0] & 0xFFuL));
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51
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52 if ((err = mp_div_2d(&t, (j == ((size - nail_bytes) - 1u)) ? (int)(8u - odd_nails) : 8, &t, NULL)) != MP_OKAY) {
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53 goto LBL_ERR;
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54 }
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55
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56 }
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57 }
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58
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59 if (written != NULL) {
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60 *written = count;
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61 }
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62 err = MP_OKAY;
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63
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64 LBL_ERR:
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65 mp_clear(&t);
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66 return err;
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67 }
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68
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69 #endif