Clean out a pile of cruft from ssl3_get_client_kex_ecdhe_ecp().

For pure ECDHE we do not need to construct a new key using the one that
was set up during the other half of the key exchange. Also, since we do not
support any form of ECDH the n == 0 case is not valid (per RFC 4492 section
5.7), so we can ditch this entirely.

ok inoguchi@ tb@

1 files changed, 38 insertions, 93 deletions

diff --git a/src/lib/libssl/ssl_srvr.c b/src/lib/libssl/ssl_srvr.c
index 94e263ad3c..b1861caa75 100644
--- a/src/lib/libssl/ssl_srvr.c
+++ b/src/lib/libssl/ssl_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_srvr.c,v 1.31 2018/05/19 14:17:55 jsing Exp $ */
+/* $OpenBSD: ssl_srvr.c,v 1.32 2018/05/19 14:23:16 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1889,120 +1889,69 @@ ssl3_get_client_kex_dhe(SSL *s, unsigned char *p, long n)
 static int
 ssl3_get_client_kex_ecdhe_ecp(SSL *s, unsigned char *p, long n)
 {
-        EC_KEY *srvr_ecdh = NULL;
-        EVP_PKEY *clnt_pub_pkey = NULL;
-        EC_POINT *clnt_ecpoint = NULL;
+        EC_POINT *point = NULL;
+        const EC_GROUP *group;
         BN_CTX *bn_ctx = NULL;
-        int i, al;
-
-        int ret = 1;
+        EC_KEY *ecdh;
         int key_size;
-        const EC_KEY   *tkey;
-        const EC_GROUP *group;
-        const BIGNUM *priv_key;
-
-        /* Initialize structures for server's ECDH key pair. */
-        if ((srvr_ecdh = EC_KEY_new()) == NULL) {
-                SSLerror(s, ERR_R_MALLOC_FAILURE);
-                goto err;
-        }
+        int ret = 1;
+        int i;
 
         /*
          * Use the ephemeral values we saved when
          * generating the ServerKeyExchange message.
          */
-        tkey = S3I(s)->tmp.ecdh;
-
-        group = EC_KEY_get0_group(tkey);
-        priv_key = EC_KEY_get0_private_key(tkey);
+        ecdh = S3I(s)->tmp.ecdh;
+        group = EC_KEY_get0_group(ecdh);
 
-        if (!EC_KEY_set_group(srvr_ecdh, group) ||
-            !EC_KEY_set_private_key(srvr_ecdh, priv_key)) {
-                SSLerror(s, ERR_R_EC_LIB);
+        /* Let's get client's public key */
+        if ((point = EC_POINT_new(group)) == NULL) {
+                SSLerror(s, ERR_R_MALLOC_FAILURE);
                 goto err;
         }
 
-        /* Let's get client's public key */
-        if ((clnt_ecpoint = EC_POINT_new(group)) == NULL) {
+        /*
+         * Get client's public key from encoded point
+         * in the ClientKeyExchange message.
+         */
+        if ((bn_ctx = BN_CTX_new()) == NULL) {
                 SSLerror(s, ERR_R_MALLOC_FAILURE);
                 goto err;
         }
 
-        if (n == 0L) {
-                /* Client Publickey was in Client Certificate */
-                if (((clnt_pub_pkey = X509_get_pubkey(
-                    s->session->peer)) == NULL) ||
-                    (clnt_pub_pkey->type != EVP_PKEY_EC)) {
-                        /*
-                         * XXX: For now, we do not support client
-                         * authentication using ECDH certificates
-                         * so this branch (n == 0L) of the code is
-                         * never executed. When that support is
-                         * added, we ought to ensure the key
-                         * received in the certificate is
-                         * authorized for key agreement.
-                         * ECDH_compute_key implicitly checks that
-                         * the two ECDH shares are for the same
-                         * group.
-                         */
-                        al = SSL_AD_HANDSHAKE_FAILURE;
-                        SSLerror(s, SSL_R_UNABLE_TO_DECODE_ECDH_CERTS);
-                        goto f_err;
-                }
-
-                if (EC_POINT_copy(clnt_ecpoint,
-                    EC_KEY_get0_public_key(clnt_pub_pkey->pkey.ec))
-                    == 0) {
-                        SSLerror(s, ERR_R_EC_LIB);
-                        goto err;
-                }
-                ret = 2; /* Skip certificate verify processing */
-        } else {
-                /*
-                 * Get client's public key from encoded point
-                 * in the ClientKeyExchange message.
-                 */
-                if ((bn_ctx = BN_CTX_new()) == NULL) {
-                        SSLerror(s, ERR_R_MALLOC_FAILURE);
-                        goto err;
-                }
-
-                /* Get encoded point length */
-                i = *p;
-
-                p += 1;
-                if (n != 1 + i) {
-                        SSLerror(s, ERR_R_EC_LIB);
-                        goto err;
-                }
-                if (EC_POINT_oct2point(group,
-                        clnt_ecpoint, p, i, bn_ctx) == 0) {
-                        SSLerror(s, ERR_R_EC_LIB);
-                        goto err;
-                }
-                /*
-                 * p is pointing to somewhere in the buffer
-                 * currently, so set it to the start.
-                 */
-                p = (unsigned char *)s->internal->init_buf->data;
+        /* Get encoded point length */
+        if (n < 1)
+                goto err;
+        i = *p;
+        p += 1;
+        if (n != 1 + i) {
+                SSLerror(s, ERR_R_EC_LIB);
+                goto err;
         }
+        if (EC_POINT_oct2point(group, point, p, i, bn_ctx) == 0) {
+                SSLerror(s, ERR_R_EC_LIB);
+                goto err;
+        }
+
+        /*
+         * p is pointing to somewhere in the buffer
+         * currently, so set it to the start.
+         */
+        p = (unsigned char *)s->internal->init_buf->data;
 
         /* Compute the shared pre-master secret */
-        key_size = ECDH_size(srvr_ecdh);
+        key_size = ECDH_size(ecdh);
         if (key_size <= 0) {
                 SSLerror(s, ERR_R_ECDH_LIB);
                 goto err;
         }
-        i = ECDH_compute_key(p, key_size, clnt_ecpoint, srvr_ecdh,
-            NULL);
+        i = ECDH_compute_key(p, key_size, point, ecdh, NULL);
         if (i <= 0) {
                 SSLerror(s, ERR_R_ECDH_LIB);
                 goto err;
         }
 
-        EVP_PKEY_free(clnt_pub_pkey);
-        EC_POINT_free(clnt_ecpoint);
-        EC_KEY_free(srvr_ecdh);
+        EC_POINT_free(point);
         BN_CTX_free(bn_ctx);
         EC_KEY_free(S3I(s)->tmp.ecdh);
         S3I(s)->tmp.ecdh = NULL;
@@ -2015,12 +1964,8 @@ ssl3_get_client_kex_ecdhe_ecp(SSL *s, unsigned char *p, long n)
         explicit_bzero(p, i);
         return (ret);
 
- f_err:
-        ssl3_send_alert(s, SSL3_AL_FATAL, al);
  err:
-        EVP_PKEY_free(clnt_pub_pkey);
-        EC_POINT_free(clnt_ecpoint);
-        EC_KEY_free(srvr_ecdh);
+        EC_POINT_free(point);
         BN_CTX_free(bn_ctx);
         return (-1);
 }