b54c312497
2 known bugs: . Build doesn't copy libssh* to the destination directory. + workaround is to copy them from the lib directory to destination and recreate links . ssh_config and sshd_config don't install + workaround is to copy them manually Note the software doesn't build to completion until you do the workarounds. Still trying to sort this out, but wanted to get these changes up for more visibility and collaboration.
399 lines
11 KiB
C
399 lines
11 KiB
C
/* $OpenBSD: dh.c,v 1.57 2015/05/27 23:39:18 dtucker Exp $ */
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/*
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* Copyright (c) 2000 Niels Provos. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/param.h> /* MIN */
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#include <openssl/bn.h>
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#include <openssl/dh.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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#include "dh.h"
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#include "pathnames.h"
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#include "log.h"
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#include "misc.h"
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#include "ssherr.h"
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static int
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parse_prime(int linenum, char *line, struct dhgroup *dhg)
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{
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char *cp, *arg;
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char *strsize, *gen, *prime;
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const char *errstr = NULL;
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long long n;
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dhg->p = dhg->g = NULL;
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cp = line;
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if ((arg = strdelim(&cp)) == NULL)
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return 0;
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/* Ignore leading whitespace */
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if (*arg == '\0')
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arg = strdelim(&cp);
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if (!arg || !*arg || *arg == '#')
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return 0;
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/* time */
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if (cp == NULL || *arg == '\0')
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goto truncated;
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arg = strsep(&cp, " "); /* type */
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if (cp == NULL || *arg == '\0')
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goto truncated;
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/* Ensure this is a safe prime */
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n = strtonum(arg, 0, 5, &errstr);
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if (errstr != NULL || n != MODULI_TYPE_SAFE) {
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error("moduli:%d: type is not %d", linenum, MODULI_TYPE_SAFE);
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goto fail;
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}
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arg = strsep(&cp, " "); /* tests */
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if (cp == NULL || *arg == '\0')
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goto truncated;
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/* Ensure prime has been tested and is not composite */
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n = strtonum(arg, 0, 0x1f, &errstr);
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if (errstr != NULL ||
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(n & MODULI_TESTS_COMPOSITE) || !(n & ~MODULI_TESTS_COMPOSITE)) {
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error("moduli:%d: invalid moduli tests flag", linenum);
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goto fail;
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}
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arg = strsep(&cp, " "); /* tries */
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if (cp == NULL || *arg == '\0')
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goto truncated;
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n = strtonum(arg, 0, 1<<30, &errstr);
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if (errstr != NULL || n == 0) {
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error("moduli:%d: invalid primality trial count", linenum);
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goto fail;
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}
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strsize = strsep(&cp, " "); /* size */
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if (cp == NULL || *strsize == '\0' ||
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(dhg->size = (int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 ||
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errstr) {
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error("moduli:%d: invalid prime length", linenum);
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goto fail;
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}
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/* The whole group is one bit larger */
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dhg->size++;
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gen = strsep(&cp, " "); /* gen */
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if (cp == NULL || *gen == '\0')
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goto truncated;
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prime = strsep(&cp, " "); /* prime */
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if (cp != NULL || *prime == '\0') {
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truncated:
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error("moduli:%d: truncated", linenum);
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goto fail;
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}
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if ((dhg->g = BN_new()) == NULL ||
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(dhg->p = BN_new()) == NULL) {
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error("parse_prime: BN_new failed");
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goto fail;
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}
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if (BN_hex2bn(&dhg->g, gen) == 0) {
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error("moduli:%d: could not parse generator value", linenum);
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goto fail;
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}
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if (BN_hex2bn(&dhg->p, prime) == 0) {
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error("moduli:%d: could not parse prime value", linenum);
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goto fail;
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}
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if (BN_num_bits(dhg->p) != dhg->size) {
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error("moduli:%d: prime has wrong size: actual %d listed %d",
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linenum, BN_num_bits(dhg->p), dhg->size - 1);
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goto fail;
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}
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if (BN_cmp(dhg->g, BN_value_one()) <= 0) {
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error("moduli:%d: generator is invalid", linenum);
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goto fail;
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}
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return 1;
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fail:
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if (dhg->g != NULL)
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BN_clear_free(dhg->g);
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if (dhg->p != NULL)
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BN_clear_free(dhg->p);
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dhg->g = dhg->p = NULL;
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return 0;
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}
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DH *
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choose_dh(int min, int wantbits, int max)
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{
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FILE *f;
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char line[4096];
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int best, bestcount, which;
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int linenum;
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struct dhgroup dhg;
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if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL &&
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(f = fopen(_PATH_DH_PRIMES, "r")) == NULL) {
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logit("WARNING: %s does not exist, using fixed modulus",
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_PATH_DH_MODULI);
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return (dh_new_group_fallback(max));
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}
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linenum = 0;
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best = bestcount = 0;
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while (fgets(line, sizeof(line), f)) {
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linenum++;
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if (!parse_prime(linenum, line, &dhg))
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continue;
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BN_clear_free(dhg.g);
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BN_clear_free(dhg.p);
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if (dhg.size > max || dhg.size < min)
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continue;
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if ((dhg.size > wantbits && dhg.size < best) ||
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(dhg.size > best && best < wantbits)) {
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best = dhg.size;
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bestcount = 0;
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}
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if (dhg.size == best)
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bestcount++;
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}
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rewind(f);
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if (bestcount == 0) {
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fclose(f);
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logit("WARNING: no suitable primes in %s", _PATH_DH_PRIMES);
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return (dh_new_group_fallback(max));
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}
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linenum = 0;
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which = arc4random_uniform(bestcount);
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while (fgets(line, sizeof(line), f)) {
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if (!parse_prime(linenum, line, &dhg))
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continue;
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if ((dhg.size > max || dhg.size < min) ||
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dhg.size != best ||
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linenum++ != which) {
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BN_clear_free(dhg.g);
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BN_clear_free(dhg.p);
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continue;
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}
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break;
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}
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fclose(f);
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if (linenum != which+1) {
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logit("WARNING: line %d disappeared in %s, giving up",
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which, _PATH_DH_PRIMES);
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return (dh_new_group_fallback(max));
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}
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return (dh_new_group(dhg.g, dhg.p));
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}
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/* diffie-hellman-groupN-sha1 */
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int
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dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
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{
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int i;
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int n = BN_num_bits(dh_pub);
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int bits_set = 0;
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BIGNUM *tmp;
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if (dh_pub->neg) {
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logit("invalid public DH value: negative");
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return 0;
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}
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if (BN_cmp(dh_pub, BN_value_one()) != 1) { /* pub_exp <= 1 */
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logit("invalid public DH value: <= 1");
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return 0;
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}
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if ((tmp = BN_new()) == NULL) {
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error("%s: BN_new failed", __func__);
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return 0;
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}
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if (!BN_sub(tmp, dh->p, BN_value_one()) ||
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BN_cmp(dh_pub, tmp) != -1) { /* pub_exp > p-2 */
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BN_clear_free(tmp);
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logit("invalid public DH value: >= p-1");
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return 0;
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}
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BN_clear_free(tmp);
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for (i = 0; i <= n; i++)
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if (BN_is_bit_set(dh_pub, i))
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bits_set++;
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debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p));
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/* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */
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if (bits_set > 1)
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return 1;
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logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p));
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return 0;
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}
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int
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dh_gen_key(DH *dh, int need)
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{
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int pbits;
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if (need < 0 || dh->p == NULL ||
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(pbits = BN_num_bits(dh->p)) <= 0 ||
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need > INT_MAX / 2 || 2 * need > pbits)
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return SSH_ERR_INVALID_ARGUMENT;
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dh->length = MIN(need * 2, pbits - 1);
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if (DH_generate_key(dh) == 0 ||
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!dh_pub_is_valid(dh, dh->pub_key)) {
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BN_clear_free(dh->priv_key);
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return SSH_ERR_LIBCRYPTO_ERROR;
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}
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return 0;
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}
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DH *
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dh_new_group_asc(const char *gen, const char *modulus)
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{
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DH *dh;
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if ((dh = DH_new()) == NULL)
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return NULL;
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if (BN_hex2bn(&dh->p, modulus) == 0 ||
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BN_hex2bn(&dh->g, gen) == 0) {
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DH_free(dh);
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return NULL;
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}
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return (dh);
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}
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/*
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* This just returns the group, we still need to generate the exchange
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* value.
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*/
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DH *
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dh_new_group(BIGNUM *gen, BIGNUM *modulus)
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{
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DH *dh;
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if ((dh = DH_new()) == NULL)
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return NULL;
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dh->p = modulus;
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dh->g = gen;
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return (dh);
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}
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DH *
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dh_new_group1(void)
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{
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static char *gen = "2", *group1 =
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"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
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"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
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"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
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"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
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"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
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"FFFFFFFF" "FFFFFFFF";
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return (dh_new_group_asc(gen, group1));
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}
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DH *
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dh_new_group14(void)
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{
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static char *gen = "2", *group14 =
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"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
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"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
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"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
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"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
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"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
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"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
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"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
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"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
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"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
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"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
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"15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF";
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return (dh_new_group_asc(gen, group14));
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}
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/*
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* 4k bit fallback group used by DH-GEX if moduli file cannot be read.
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* Source: MODP group 16 from RFC3526.
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*/
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DH *
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dh_new_group_fallback(int max)
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{
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static char *gen = "2", *group16 =
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"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
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"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
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"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
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"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
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"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
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"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
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"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
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"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
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"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
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"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
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"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
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"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
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"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
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"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
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"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
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"43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
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"88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
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"2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
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"287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
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"1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
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"93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34063199"
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"FFFFFFFF" "FFFFFFFF";
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if (max < 4096) {
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debug3("requested max size %d, using 2k bit group 14", max);
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return dh_new_group14();
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}
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debug3("using 4k bit group 16");
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return (dh_new_group_asc(gen, group16));
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}
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/*
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* Estimates the group order for a Diffie-Hellman group that has an
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* attack complexity approximately the same as O(2**bits).
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* Values from NIST Special Publication 800-57: Recommendation for Key
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* Management Part 1 (rev 3) limited by the recommended maximum value
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* from RFC4419 section 3.
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*/
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u_int
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dh_estimate(int bits)
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{
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if (bits <= 112)
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return 2048;
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if (bits <= 128)
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return 3072;
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if (bits <= 192)
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return 7680;
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return 8192;
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}
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