Mercurial > dropbear
view libtommath/bn_mp_and.c @ 1861:2b3a8026a6ce
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 |
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#include "tommath_private.h" #ifdef BN_MP_AND_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* two complement and */ mp_err mp_and(const mp_int *a, const mp_int *b, mp_int *c) { int used = MP_MAX(a->used, b->used) + 1, i; mp_err err; mp_digit ac = 1, bc = 1, cc = 1; mp_sign csign = ((a->sign == MP_NEG) && (b->sign == MP_NEG)) ? MP_NEG : MP_ZPOS; if (c->alloc < used) { if ((err = mp_grow(c, used)) != MP_OKAY) { return err; } } for (i = 0; i < used; i++) { mp_digit x, y; /* convert to two complement if negative */ if (a->sign == MP_NEG) { ac += (i >= a->used) ? MP_MASK : (~a->dp[i] & MP_MASK); x = ac & MP_MASK; ac >>= MP_DIGIT_BIT; } else { x = (i >= a->used) ? 0uL : a->dp[i]; } /* convert to two complement if negative */ if (b->sign == MP_NEG) { bc += (i >= b->used) ? MP_MASK : (~b->dp[i] & MP_MASK); y = bc & MP_MASK; bc >>= MP_DIGIT_BIT; } else { y = (i >= b->used) ? 0uL : b->dp[i]; } c->dp[i] = x & y; /* convert to to sign-magnitude if negative */ if (csign == MP_NEG) { cc += ~c->dp[i] & MP_MASK; c->dp[i] = cc & MP_MASK; cc >>= MP_DIGIT_BIT; } } c->used = used; c->sign = csign; mp_clamp(c); return MP_OKAY; } #endif