1 files changed, 29 insertions, 80 deletions

diff --git a/kexgexc.c b/kexgexc.c
index 0d07f73c7..1c65b8a18 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.27 2018/02/07 02:06:51 jsing Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.34 2019/01/23 00:30:41 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -100,13 +100,8 @@ input_kex_dh_gex_group(int type, u_int32_t seq, struct ssh *ssh)
 
         debug("got SSH2_MSG_KEX_DH_GEX_GROUP");
 
-        if ((p = BN_new()) == NULL ||
-            (g = BN_new()) == NULL) {
-                r = SSH_ERR_ALLOC_FAIL;
-                goto out;
-        }
-        if ((r = sshpkt_get_bignum2(ssh, p)) != 0 ||
-            (r = sshpkt_get_bignum2(ssh, g)) != 0 ||
+        if ((r = sshpkt_get_bignum2(ssh, &p)) != 0 ||
+            (r = sshpkt_get_bignum2(ssh, &g)) != 0 ||
             (r = sshpkt_get_end(ssh)) != 0)
                 goto out;
         if ((bits = BN_num_bits(p)) < 0 ||
@@ -148,71 +143,39 @@ static int
 input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
 {
         struct kex *kex = ssh->kex;
-        BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
+        BIGNUM *dh_server_pub = NULL;
         const BIGNUM *pub_key, *dh_p, *dh_g;
+        struct sshbuf *shared_secret = NULL;
+        struct sshbuf *tmp = NULL, *server_host_key_blob = NULL;
         struct sshkey *server_host_key = NULL;
-        u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
+        u_char *signature = NULL;
         u_char hash[SSH_DIGEST_MAX_LENGTH];
-        size_t klen = 0, slen, sbloblen, hashlen;
-        int kout, r;
+        size_t slen, hashlen;
+        int r;
 
         debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
-        if (kex->verify_host_key == NULL) {
-                r = SSH_ERR_INVALID_ARGUMENT;
-                goto out;
-        }
         /* key, cert */
-        if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
-            &sbloblen)) != 0 ||
-            (r = sshkey_from_blob(server_host_key_blob, sbloblen,
-            &server_host_key)) != 0)
+        if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
                 goto out;
-        if (server_host_key->type != kex->hostkey_type ||
-            (kex->hostkey_type == KEY_ECDSA &&
-            server_host_key->ecdsa_nid != kex->hostkey_nid)) {
-                r = SSH_ERR_KEY_TYPE_MISMATCH;
-                goto out;
-        }
-        if (kex->verify_host_key(server_host_key, ssh) == -1) {
-                r = SSH_ERR_SIGNATURE_INVALID;
-                goto out;
-        }
-        /* DH parameter f, server public DH key */
-        if ((dh_server_pub = BN_new()) == NULL) {
+        /* sshkey_fromb() consumes its buffer, so make a copy */
+        if ((tmp = sshbuf_fromb(server_host_key_blob)) == NULL) {
                 r = SSH_ERR_ALLOC_FAIL;
                 goto out;
         }
-        /* signed H */
-        if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
+        if ((r = sshkey_fromb(tmp, &server_host_key)) != 0 ||
+            (r = kex_verify_host_key(ssh, server_host_key)) != 0)
+                goto out;
+        /* DH parameter f, server public DH key, signed H */
+        if ((r = sshpkt_get_bignum2(ssh, &dh_server_pub)) != 0 ||
             (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
             (r = sshpkt_get_end(ssh)) != 0)
                 goto out;
-#ifdef DEBUG_KEXDH
-        fprintf(stderr, "dh_server_pub= ");
-        BN_print_fp(stderr, dh_server_pub);
-        fprintf(stderr, "\n");
-        debug("bits %d", BN_num_bits(dh_server_pub));
-#endif
-        if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
-                sshpkt_disconnect(ssh, "bad server public DH value");
-                r = SSH_ERR_MESSAGE_INCOMPLETE;
-                goto out;
-        }
-
-        klen = DH_size(kex->dh);
-        if ((kbuf = malloc(klen)) == NULL ||
-            (shared_secret = BN_new()) == NULL) {
+        if ((shared_secret = sshbuf_new()) == NULL) {
                 r = SSH_ERR_ALLOC_FAIL;
                 goto out;
         }
-        if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 ||
-            BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
-                r = SSH_ERR_LIBCRYPTO_ERROR;
+        if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0)
                 goto out;
-        }
-#ifdef DEBUG_KEXDH
-        dump_digest("shared secret", kbuf, kout);
-#endif
         if (ssh->compat & SSH_OLD_DHGEX)
                 kex->min = kex->max = -1;
 
@@ -222,16 +185,16 @@ input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
         hashlen = sizeof(hash);
         if ((r = kexgex_hash(
             kex->hash_alg,
-            kex->client_version_string,
-            kex->server_version_string,
-            sshbuf_ptr(kex->my), sshbuf_len(kex->my),
-            sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
-            server_host_key_blob, sbloblen,
+            kex->client_version,
+            kex->server_version,
+            kex->my,
+            kex->peer,
+            server_host_key_blob,
             kex->min, kex->nbits, kex->max,
             dh_p, dh_g,
             pub_key,
             dh_server_pub,
-            shared_secret,
+            sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
             hash, &hashlen)) != 0)
                 goto out;
 
@@ -239,31 +202,17 @@ input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
             hashlen, kex->hostkey_alg, ssh->compat)) != 0)
                 goto out;
 
-        /* save session id */
-        if (kex->session_id == NULL) {
-                kex->session_id_len = hashlen;
-                kex->session_id = malloc(kex->session_id_len);
-                if (kex->session_id == NULL) {
-                        r = SSH_ERR_ALLOC_FAIL;
-                        goto out;
-                }
-                memcpy(kex->session_id, hash, kex->session_id_len);
-        }
-
-        if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
+        if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
                 r = kex_send_newkeys(ssh);
  out:
         explicit_bzero(hash, sizeof(hash));
         DH_free(kex->dh);
         kex->dh = NULL;
         BN_clear_free(dh_server_pub);
-        if (kbuf) {
-                explicit_bzero(kbuf, klen);
-                free(kbuf);
-        }
-        BN_clear_free(shared_secret);
+        sshbuf_free(shared_secret);
         sshkey_free(server_host_key);
-        free(server_host_key_blob);
+        sshbuf_free(tmp);
+        sshbuf_free(server_host_key_blob);
         free(signature);
         return r;
 }