X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/f11fe301db707c84444c626beaa73b2adc1207ac..ca24b5507e1129858ef7c87a4549f0e44237a7b1:/dh.c diff --git a/dh.c b/dh.c index 6ec37867..b9029d86 100644 --- a/dh.c +++ b/dh.c @@ -1,3 +1,4 @@ +/* $OpenBSD: dh.c,v 1.48 2009/10/01 11:37:33 grunk Exp $ */ /* * Copyright (c) 2000 Niels Provos. All rights reserved. * @@ -23,17 +24,17 @@ */ #include "includes.h" -RCSID("$OpenBSD: dh.c,v 1.22 2002/06/27 08:49:44 markus Exp $"); -#include "xmalloc.h" +#include #include #include -#include -#include "buffer.h" -#include "cipher.h" -#include "kex.h" +#include +#include +#include +#include + #include "dh.h" #include "pathnames.h" #include "log.h" @@ -44,9 +45,12 @@ parse_prime(int linenum, char *line, struct dhgroup *dhg) { char *cp, *arg; char *strsize, *gen, *prime; + const char *errstr = NULL; + long long n; cp = line; - arg = strdelim(&cp); + if ((arg = strdelim(&cp)) == NULL) + return 0; /* Ignore leading whitespace */ if (*arg == '\0') arg = strdelim(&cp); @@ -59,15 +63,28 @@ parse_prime(int linenum, char *line, struct dhgroup *dhg) arg = strsep(&cp, " "); /* type */ if (cp == NULL || *arg == '\0') goto fail; + /* Ensure this is a safe prime */ + n = strtonum(arg, 0, 5, &errstr); + if (errstr != NULL || n != MODULI_TYPE_SAFE) + goto fail; arg = strsep(&cp, " "); /* tests */ if (cp == NULL || *arg == '\0') goto fail; + /* Ensure prime has been tested and is not composite */ + n = strtonum(arg, 0, 0x1f, &errstr); + if (errstr != NULL || + (n & MODULI_TESTS_COMPOSITE) || !(n & ~MODULI_TESTS_COMPOSITE)) + goto fail; arg = strsep(&cp, " "); /* tries */ if (cp == NULL || *arg == '\0') goto fail; + n = strtonum(arg, 0, 1<<30, &errstr); + if (errstr != NULL || n == 0) + goto fail; strsize = strsep(&cp, " "); /* size */ if (cp == NULL || *strsize == '\0' || - (dhg->size = atoi(strsize)) == 0) + (dhg->size = (int)strtonum(strsize, 0, 64*1024, &errstr)) == 0 || + errstr) goto fail; /* The whole group is one bit larger */ dhg->size++; @@ -91,6 +108,9 @@ parse_prime(int linenum, char *line, struct dhgroup *dhg) if (BN_num_bits(dhg->p) != dhg->size) goto failclean; + if (BN_is_zero(dhg->g) || BN_is_one(dhg->g)) + goto failclean; + return (1); failclean: @@ -105,15 +125,16 @@ DH * choose_dh(int min, int wantbits, int max) { FILE *f; - char line[2048]; + char line[4096]; int best, bestcount, which; int linenum; struct dhgroup dhg; if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL && (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) { - log("WARNING: %s does not exist, using old modulus", _PATH_DH_MODULI); - return (dh_new_group1()); + logit("WARNING: %s does not exist, using fixed modulus", + _PATH_DH_MODULI); + return (dh_new_group14()); } linenum = 0; @@ -140,12 +161,12 @@ choose_dh(int min, int wantbits, int max) if (bestcount == 0) { fclose(f); - log("WARNING: no suitable primes in %s", _PATH_DH_PRIMES); - return (NULL); + logit("WARNING: no suitable primes in %s", _PATH_DH_PRIMES); + return (dh_new_group14()); } linenum = 0; - which = arc4random() % bestcount; + which = arc4random_uniform(bestcount); while (fgets(line, sizeof(line), f)) { if (!parse_prime(linenum, line, &dhg)) continue; @@ -166,7 +187,7 @@ choose_dh(int min, int wantbits, int max) return (dh_new_group(dhg.g, dhg.p)); } -/* diffie-hellman-group1-sha1 */ +/* diffie-hellman-groupN-sha1 */ int dh_pub_is_valid(DH *dh, BIGNUM *dh_pub) @@ -174,31 +195,50 @@ dh_pub_is_valid(DH *dh, BIGNUM *dh_pub) int i; int n = BN_num_bits(dh_pub); int bits_set = 0; + BIGNUM *tmp; if (dh_pub->neg) { - log("invalid public DH value: negativ"); + logit("invalid public DH value: negative"); + return 0; + } + if (BN_cmp(dh_pub, BN_value_one()) != 1) { /* pub_exp <= 1 */ + logit("invalid public DH value: <= 1"); + return 0; + } + + if ((tmp = BN_new()) == NULL) { + error("%s: BN_new failed", __func__); return 0; } + if (!BN_sub(tmp, dh->p, BN_value_one()) || + BN_cmp(dh_pub, tmp) != -1) { /* pub_exp > p-2 */ + BN_clear_free(tmp); + logit("invalid public DH value: >= p-1"); + return 0; + } + BN_clear_free(tmp); + for (i = 0; i <= n; i++) if (BN_is_bit_set(dh_pub, i)) bits_set++; - debug("bits set: %d/%d", bits_set, BN_num_bits(dh->p)); + debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p)); /* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */ - if (bits_set > 1 && (BN_cmp(dh_pub, dh->p) == -1)) + if (bits_set > 1) return 1; - log("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p)); + + logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p)); return 0; } void dh_gen_key(DH *dh, int need) { - int i, bits_set = 0, tries = 0; + int i, bits_set, tries = 0; if (dh->p == NULL) fatal("dh_gen_key: dh->p == NULL"); - if (2*need >= BN_num_bits(dh->p)) + if (need > INT_MAX / 2 || 2 * need >= BN_num_bits(dh->p)) fatal("dh_gen_key: group too small: %d (2*need %d)", BN_num_bits(dh->p), 2*need); do { @@ -211,10 +251,10 @@ dh_gen_key(DH *dh, int need) fatal("dh_gen_key: BN_rand failed"); if (DH_generate_key(dh) == 0) fatal("DH_generate_key"); - for (i = 0; i <= BN_num_bits(dh->priv_key); i++) + for (i = 0, bits_set = 0; i <= BN_num_bits(dh->priv_key); i++) if (BN_is_bit_set(dh->priv_key, i)) bits_set++; - debug("dh_gen_key: priv key bits set: %d/%d", + debug2("dh_gen_key: priv key bits set: %d/%d", bits_set, BN_num_bits(dh->priv_key)); if (tries++ > 10) fatal("dh_gen_key: too many bad keys: giving up"); @@ -269,6 +309,25 @@ dh_new_group1(void) return (dh_new_group_asc(gen, group1)); } +DH * +dh_new_group14(void) +{ + static char *gen = "2", *group14 = + "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1" + "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD" + "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245" + "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED" + "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D" + "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F" + "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D" + "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B" + "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9" + "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510" + "15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF"; + + return (dh_new_group_asc(gen, group14)); +} + /* * Estimates the group order for a Diffie-Hellman group that has an * attack complexity approximately the same as O(2**bits). Estimate @@ -279,11 +338,9 @@ int dh_estimate(int bits) { - if (bits < 64) - return (512); /* O(2**63) */ - if (bits < 128) + if (bits <= 128) return (1024); /* O(2**86) */ - if (bits < 192) + if (bits <= 192) return (2048); /* O(2**116) */ return (4096); /* O(2**156) */ }