Convert ssl3_get_client_kex_gost() to CBS.

ok beck@ tb@

1 files changed, 23 insertions, 21 deletions

diff --git a/src/lib/libssl/ssl_srvr.c b/src/lib/libssl/ssl_srvr.c
index 3da9cacd7d..94e263ad3c 100644
--- a/src/lib/libssl/ssl_srvr.c
+++ b/src/lib/libssl/ssl_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_srvr.c,v 1.30 2018/05/13 15:51:29 jsing Exp $ */
+/* $OpenBSD: ssl_srvr.c,v 1.31 2018/05/19 14:17:55 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -2073,24 +2073,30 @@ ssl3_get_client_kex_ecdhe(SSL *s, unsigned char *p, long n)
 static int
 ssl3_get_client_kex_gost(SSL *s, unsigned char *p, long n)
 {
-
         EVP_PKEY_CTX *pkey_ctx;
         EVP_PKEY *client_pub_pkey = NULL, *pk = NULL;
-        unsigned char premaster_secret[32], *start;
-        size_t outlen = 32, inlen;
+        unsigned char premaster_secret[32];
         unsigned long alg_a;
-        int Ttag, Tclass;
-        long Tlen;
+        size_t outlen = 32;
+        CBS cbs, gostblob;
         int al;
         int ret = 0;
 
+        if (n < 0)
+                goto err;
+
+        CBS_init(&cbs, p, n);
+
         /* Get our certificate private key*/
         alg_a = S3I(s)->hs.new_cipher->algorithm_auth;
         if (alg_a & SSL_aGOST01)
                 pk = s->cert->pkeys[SSL_PKEY_GOST01].privatekey;
 
-        pkey_ctx = EVP_PKEY_CTX_new(pk, NULL);
-        EVP_PKEY_decrypt_init(pkey_ctx);
+        if ((pkey_ctx = EVP_PKEY_CTX_new(pk, NULL)) == NULL)
+                goto err;
+        if (EVP_PKEY_decrypt_init(pkey_ctx) <= 0)
+                goto gerr;
+
         /*
          * If client certificate is present and is of the same type,
          * maybe use it for key exchange.
@@ -2098,32 +2104,28 @@ ssl3_get_client_kex_gost(SSL *s, unsigned char *p, long n)
          * it is completely valid to use a client certificate for
          * authorization only.
          */
-        client_pub_pkey = X509_get_pubkey(s->session->peer);
-        if (client_pub_pkey) {
+        if ((client_pub_pkey = X509_get_pubkey(s->session->peer)) != NULL) {
                 if (EVP_PKEY_derive_set_peer(pkey_ctx,
                     client_pub_pkey) <= 0)
                         ERR_clear_error();
         }
-        if (2 > n)
-                goto truncated;
+
         /* Decrypt session key */
-        if (ASN1_get_object((const unsigned char **)&p, &Tlen, &Ttag,
-            &Tclass, n) != V_ASN1_CONSTRUCTED ||
-            Ttag != V_ASN1_SEQUENCE || Tclass != V_ASN1_UNIVERSAL) {
-                SSLerror(s, SSL_R_DECRYPTION_FAILED);
-                goto gerr;
-        }
-        start = p;
-        inlen = Tlen;
+        if (!CBS_get_asn1(&cbs, &gostblob, CBS_ASN1_SEQUENCE))
+                goto truncated;
+        if (CBS_len(&cbs) != 0)
+                goto truncated;
         if (EVP_PKEY_decrypt(pkey_ctx, premaster_secret, &outlen,
-            start, inlen) <=0) {
+            CBS_data(&gostblob), CBS_len(&gostblob)) <= 0) {
                 SSLerror(s, SSL_R_DECRYPTION_FAILED);
                 goto gerr;
         }
+
         /* Generate master secret */
         s->session->master_key_length =
             tls1_generate_master_secret(
                 s, s->session->master_key, premaster_secret, 32);
+
         /* Check if pubkey from client certificate was used */
         if (EVP_PKEY_CTX_ctrl(pkey_ctx, -1, -1,
             EVP_PKEY_CTRL_PEER_KEY, 2, NULL) > 0)