Mercurial > dropbear
view libtommath/bn_s_mp_rand_jenkins.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_S_MP_RAND_JENKINS_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* Bob Jenkins' http://burtleburtle.net/bob/rand/smallprng.html */ /* Chosen for speed and a good "mix" */ typedef struct { uint64_t a; uint64_t b; uint64_t c; uint64_t d; } ranctx; static ranctx jenkins_x; #define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) static uint64_t s_rand_jenkins_val(void) { uint64_t e = jenkins_x.a - rot(jenkins_x.b, 7); jenkins_x.a = jenkins_x.b ^ rot(jenkins_x.c, 13); jenkins_x.b = jenkins_x.c + rot(jenkins_x.d, 37); jenkins_x.c = jenkins_x.d + e; jenkins_x.d = e + jenkins_x.a; return jenkins_x.d; } void s_mp_rand_jenkins_init(uint64_t seed) { uint64_t i; jenkins_x.a = 0xf1ea5eedULL; jenkins_x.b = jenkins_x.c = jenkins_x.d = seed; for (i = 0uLL; i < 20uLL; ++i) { (void)s_rand_jenkins_val(); } } mp_err s_mp_rand_jenkins(void *p, size_t n) { char *q = (char *)p; while (n > 0u) { int i; uint64_t x = s_rand_jenkins_val(); for (i = 0; (i < 8) && (n > 0u); ++i, --n) { *q++ = (char)(x & 0xFFuLL); x >>= 8; } } return MP_OKAY; } #endif