1 files changed, 47 insertions, 29 deletions

diff --git a/dh.c b/dh.c
index ac8d5a0ae..657b32da3 100644
--- a/dh.c
+++ b/dh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dh.c,v 1.66 2018/08/04 00:55:06 djm Exp $ */
+/* $OpenBSD: dh.c,v 1.68 2018/09/17 15:40:14 millert Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  *
@@ -43,6 +43,8 @@
 #include "misc.h"
 #include "ssherr.h"
 
+#include "openbsd-compat/openssl-compat.h"
+
 static int
 parse_prime(int linenum, char *line, struct dhgroup *dhg)
 {
@@ -186,15 +188,17 @@ choose_dh(int min, int wantbits, int max)
                 logit("WARNING: no suitable primes in %s", _PATH_DH_MODULI);
                 return (dh_new_group_fallback(max));
         }
+        which = arc4random_uniform(bestcount);
 
         linenum = 0;
-        which = arc4random_uniform(bestcount);
+        bestcount = 0;
         while (getline(&line, &linesize, f) != -1) {
+                linenum++;
                 if (!parse_prime(linenum, line, &dhg))
                         continue;
                 if ((dhg.size > max || dhg.size < min) ||
                     dhg.size != best ||
-                    linenum++ != which) {
+                    bestcount++ != which) {
                         BN_clear_free(dhg.g);
                         BN_clear_free(dhg.p);
                         continue;
@@ -204,9 +208,9 @@ choose_dh(int min, int wantbits, int max)
         free(line);
         line = NULL;
         fclose(f);
-        if (linenum != which+1) {
-                logit("WARNING: line %d disappeared in %s, giving up",
-                    which, _PATH_DH_MODULI);
+        if (bestcount != which + 1) {
+                logit("WARNING: selected prime disappeared in %s, giving up",
+                    _PATH_DH_MODULI);
                 return (dh_new_group_fallback(max));
         }
 
@@ -216,14 +220,17 @@ choose_dh(int min, int wantbits, int max)
 /* diffie-hellman-groupN-sha1 */
 
 int
-dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
+dh_pub_is_valid(const DH *dh, const BIGNUM *dh_pub)
 {
         int i;
         int n = BN_num_bits(dh_pub);
         int bits_set = 0;
         BIGNUM *tmp;
+        const BIGNUM *dh_p;
+
+        DH_get0_pqg(dh, &dh_p, NULL, NULL);
 
-        if (dh_pub->neg) {
+        if (BN_is_negative(dh_pub)) {
                 logit("invalid public DH value: negative");
                 return 0;
         }
@@ -236,7 +243,7 @@ dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
                 error("%s: BN_new failed", __func__);
                 return 0;
         }
-        if (!BN_sub(tmp, dh->p, BN_value_one()) ||
+        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");
@@ -247,14 +254,14 @@ dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
         for (i = 0; i <= n; i++)
                 if (BN_is_bit_set(dh_pub, i))
                         bits_set++;
-        debug2("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 < 4) {
                 logit("invalid public DH value (%d/%d)",
-                   bits_set, BN_num_bits(dh->p));
+                   bits_set, BN_num_bits(dh_p));
                 return 0;
         }
         return 1;
@@ -264,9 +271,12 @@ int
 dh_gen_key(DH *dh, int need)
 {
         int pbits;
+        const BIGNUM *dh_p, *pub_key;
 
-        if (need < 0 || dh->p == NULL ||
-            (pbits = BN_num_bits(dh->p)) <= 0 ||
+        DH_get0_pqg(dh, &dh_p, NULL, NULL);
+
+        if (need < 0 || dh_p == NULL ||
+            (pbits = BN_num_bits(dh_p)) <= 0 ||
             need > INT_MAX / 2 || 2 * need > pbits)
                 return SSH_ERR_INVALID_ARGUMENT;
         if (need < 256)
@@ -275,13 +285,14 @@ dh_gen_key(DH *dh, int need)
          * Pollard Rho, Big step/Little Step attacks are O(sqrt(n)),
          * so double requested need here.
          */
-        dh->length = MINIMUM(need * 2, pbits - 1);
-        if (DH_generate_key(dh) == 0 ||
-            !dh_pub_is_valid(dh, dh->pub_key)) {
-                BN_clear_free(dh->priv_key);
-                dh->priv_key = NULL;
+        if (!DH_set_length(dh, MINIMUM(need * 2, pbits - 1)))
                 return SSH_ERR_LIBCRYPTO_ERROR;
-        }
+
+        if (DH_generate_key(dh) == 0)
+                return SSH_ERR_LIBCRYPTO_ERROR;
+        DH_get0_key(dh, &pub_key, NULL);
+        if (!dh_pub_is_valid(dh, pub_key))
+                return SSH_ERR_INVALID_FORMAT;
         return 0;
 }
 
@@ -289,22 +300,27 @@ DH *
 dh_new_group_asc(const char *gen, const char *modulus)
 {
         DH *dh;
+        BIGNUM *dh_p = NULL, *dh_g = NULL;
 
         if ((dh = DH_new()) == NULL)
                 return NULL;
-        if (BN_hex2bn(&dh->p, modulus) == 0 ||
-            BN_hex2bn(&dh->g, gen) == 0) {
-                DH_free(dh);
-                return NULL;
-        }
-        return (dh);
+        if (BN_hex2bn(&dh_p, modulus) == 0 ||
+            BN_hex2bn(&dh_g, gen) == 0)
+                goto fail;
+        if (!DH_set0_pqg(dh, dh_p, NULL, dh_g))
+                goto fail;
+        return dh;
+ fail:
+        DH_free(dh);
+        BN_clear_free(dh_p);
+        BN_clear_free(dh_g);
+        return NULL;
 }
 
 /*
  * This just returns the group, we still need to generate the exchange
  * value.
  */
-
 DH *
 dh_new_group(BIGNUM *gen, BIGNUM *modulus)
 {
@@ -312,10 +328,12 @@ dh_new_group(BIGNUM *gen, BIGNUM *modulus)
 
         if ((dh = DH_new()) == NULL)
                 return NULL;
-        dh->p = modulus;
-        dh->g = gen;
+        if (!DH_set0_pqg(dh, modulus, NULL, gen)) {
+                DH_free(dh);
+                return NULL;
+        }
 
-        return (dh);
+        return dh;
 }
 
 /* rfc2409 "Second Oakley Group" (1024 bits) */