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authorJoel Sing <jsing@cvs.openbsd.org>2015-09-13 12:52:08 +0000
committerJoel Sing <jsing@cvs.openbsd.org>2015-09-13 12:52:08 +0000
commitfd2af42f47b733056e17c4f7a49fead4b756e6f3 (patch)
treed903c1c7fd2de09f24360b8e45cd5cd464769198 /lib
parentbe23b55167326ff7f0f13b5754d8e685cad9ef8d (diff)
Stop generating private keys in a network buffer.
The current client key exchange code generates DH and ECDH keys into the same buffer that we use to send data to the network - stop doing this and malloc() a new buffer, which we explicit_bzero() and free() on return. This also benefits from ASLR and means that the keys are no longer generated in a well known location. ok beck@
Diffstat (limited to 'lib')
-rw-r--r--lib/libssl/src/ssl/s3_clnt.c58
1 files changed, 29 insertions, 29 deletions
diff --git a/lib/libssl/src/ssl/s3_clnt.c b/lib/libssl/src/ssl/s3_clnt.c
index e33d745b198..52b9baadbf9 100644
--- a/lib/libssl/src/ssl/s3_clnt.c
+++ b/lib/libssl/src/ssl/s3_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s3_clnt.c,v 1.134 2015/09/13 12:39:16 jsing Exp $ */
+/* $OpenBSD: s3_clnt.c,v 1.135 2015/09/13 12:52:07 jsing Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
@@ -1908,8 +1908,9 @@ static int
ssl3_client_kex_dhe(SSL *s, SESS_CERT *sess_cert, unsigned char *p, int *outlen)
{
DH *dh_srvr = NULL, *dh_clnt = NULL;
+ unsigned char *key = NULL;
+ int key_size, n;
int ret = -1;
- int n;
/* Ensure that we have an ephemeral key for DHE. */
if (sess_cert->peer_dh_tmp == NULL) {
@@ -1929,12 +1930,13 @@ ssl3_client_kex_dhe(SSL *s, SESS_CERT *sess_cert, unsigned char *p, int *outlen)
SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, ERR_R_DH_LIB);
goto err;
}
-
- /*
- * Use the 'p' output buffer for the DH key, but make sure to clear
- * it out afterwards.
- */
- n = DH_compute_key(p, dh_srvr->pub_key, dh_clnt);
+ key_size = DH_size(dh_clnt);
+ if ((key = malloc(key_size)) == NULL) {
+ SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE,
+ ERR_R_MALLOC_FAILURE);
+ goto err;
+ }
+ n = DH_compute_key(key, dh_srvr->pub_key, dh_clnt);
if (n <= 0) {
SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, ERR_R_DH_LIB);
goto err;
@@ -1943,10 +1945,7 @@ ssl3_client_kex_dhe(SSL *s, SESS_CERT *sess_cert, unsigned char *p, int *outlen)
/* Generate master key from the result. */
s->session->master_key_length =
s->method->ssl3_enc->generate_master_secret(s,
- s->session->master_key, p, n);
-
- /* Clean up. */
- explicit_bzero(p, n);
+ s->session->master_key, key, n);
/* Send off the data. */
n = BN_num_bytes(dh_clnt->pub_key);
@@ -1959,6 +1958,9 @@ ssl3_client_kex_dhe(SSL *s, SESS_CERT *sess_cert, unsigned char *p, int *outlen)
err:
DH_free(dh_clnt);
+ if (key != NULL)
+ explicit_bzero(key, key_size);
+ free(key);
return (ret);
}
@@ -1967,18 +1969,17 @@ static int
ssl3_client_kex_ecdh(SSL *s, SESS_CERT *sess_cert, unsigned char *p,
int *outlen)
{
- EC_KEY *clnt_ecdh = NULL;
+ EC_KEY *tkey, *clnt_ecdh = NULL;
const EC_GROUP *srvr_group = NULL;
const EC_POINT *srvr_ecpoint = NULL;
EVP_PKEY *srvr_pub_pkey = NULL;
BN_CTX *bn_ctx = NULL;
unsigned char *encodedPoint = NULL;
+ unsigned char *key = NULL;
unsigned long alg_k;
int encoded_pt_len = 0;
- int key_size;
- EC_KEY *tkey;
+ int key_size, n;
int ret = -1;
- int n;
alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
@@ -2025,22 +2026,21 @@ ssl3_client_kex_ecdh(SSL *s, SESS_CERT *sess_cert, unsigned char *p,
goto err;
}
- /* Generate a new ECDH key pair */
+ /* Generate a new ECDH key pair. */
if (!(EC_KEY_generate_key(clnt_ecdh))) {
SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, ERR_R_ECDH_LIB);
goto err;
}
-
- /*
- * Use the 'p' output buffer for the ECDH key, but make sure to clear
- * it out afterwards.
- */
key_size = ECDH_size(clnt_ecdh);
if (key_size <= 0) {
SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, ERR_R_ECDH_LIB);
goto err;
}
- n = ECDH_compute_key(p, key_size, srvr_ecpoint, clnt_ecdh, NULL);
+ if ((key = malloc(key_size)) == NULL) {
+ SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE,
+ ERR_R_MALLOC_FAILURE);
+ }
+ n = ECDH_compute_key(key, key_size, srvr_ecpoint, clnt_ecdh, NULL);
if (n <= 0) {
SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, ERR_R_ECDH_LIB);
goto err;
@@ -2049,10 +2049,7 @@ ssl3_client_kex_ecdh(SSL *s, SESS_CERT *sess_cert, unsigned char *p,
/* Generate master key from the result. */
s->session->master_key_length =
s->method->ssl3_enc->generate_master_secret(s,
- s->session->master_key, p, n);
-
- /* Clean up. */
- explicit_bzero(p, n);
+ s->session->master_key, key, n);
/*
* First check the size of encoding and allocate memory accordingly.
@@ -2087,7 +2084,10 @@ ssl3_client_kex_ecdh(SSL *s, SESS_CERT *sess_cert, unsigned char *p,
ret = 1;
err:
- /* Free allocated memory */
+ if (key != NULL)
+ explicit_bzero(key, key_size);
+ free(key);
+
BN_CTX_free(bn_ctx);
free(encodedPoint);
EC_KEY_free(clnt_ecdh);
@@ -2219,7 +2219,7 @@ ssl3_send_client_key_exchange(SSL *s)
SESS_CERT *sess_cert;
unsigned long alg_k;
unsigned char *p;
- int n;
+ int n = 0;
if (s->state == SSL3_ST_CW_KEY_EXCH_A) {
p = ssl3_handshake_msg_start(s, SSL3_MT_CLIENT_KEY_EXCHANGE);