This moves the OpenVPN specific PRF into its own function also
simplifies the code a bit by passing tls_session directly instead of
5 of its fields.
Signed-off-by: Arne Schwabe <a...@rfc2549.org>
Patch V2: Rebase
---
src/openvpn/ssl.c | 109 +++++++++++++++++++++++++++++-----------------
1 file changed, 69 insertions(+), 40 deletions(-)
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index 3fcaa25f..06cc4c0b 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -1765,27 +1765,38 @@ openvpn_PRF(const uint8_t *secret,
VALGRIND_MAKE_READABLE((void *)output, output_len);
}
-/*
- * Using source entropy from local and remote hosts, mix into
- * master key.
- */
-static bool
-generate_key_expansion(struct key_ctx_bi *key,
- const struct key_type *key_type,
- const struct key_source2 *key_src,
- const struct session_id *client_sid,
- const struct session_id *server_sid,
- bool server)
+static void
+init_key_contexts(struct key_ctx_bi *key,
+ const struct key_type *key_type,
+ bool server,
+ struct key2 *key2)
+{
+ /* Initialize OpenSSL key contexts */
+ int key_direction = server ? KEY_DIRECTION_INVERSE : KEY_DIRECTION_NORMAL;
+ init_key_ctx_bi(key, key2, key_direction, key_type, "Data Channel");
+
+ /* Initialize implicit IVs */
+ key_ctx_update_implicit_iv(&key->encrypt, (*key2).keys[(int)server].hmac,
+ MAX_HMAC_KEY_LENGTH);
+ key_ctx_update_implicit_iv(&key->decrypt, (*key2).keys[1-(int)server].hmac,
+ MAX_HMAC_KEY_LENGTH);
+
+}
+
+
+static struct key2
+generate_key_expansion_oepnvpn_prf(const struct tls_session *session)
{
+
uint8_t master[48] = { 0 };
- struct key2 key2 = { 0 };
- bool ret = false;
- if (key->initialized)
- {
- msg(D_TLS_ERRORS, "TLS Error: key already initialized");
- goto exit;
- }
+ const struct key_state *ks = &session->key[KS_PRIMARY];
+ const struct key_source2 *key_src = ks->key_src;
+
+ const struct session_id *client_sid = session->opt->server ?
+ &ks->session_id_remote :
&session->session_id;
+ const struct session_id *server_sid = !session->opt->server ?
+ &ks->session_id_remote :
&session->session_id;
/* debugging print of source key material */
key_source2_print(key_src);
@@ -1803,6 +1814,7 @@ generate_key_expansion(struct key_ctx_bi *key,
master,
sizeof(master));
+ struct key2 key2;
/* compute key expansion */
openvpn_PRF(master,
sizeof(master),
@@ -1815,41 +1827,62 @@ generate_key_expansion(struct key_ctx_bi *key,
server_sid,
(uint8_t *)key2.keys,
sizeof(key2.keys));
+ secure_memzero(&master, sizeof(master));
+ /* We use the DES fixup here so we can drop it once we
+ * drop DES support and non RFC5705 key derivation */
+ for (int i = 0; i < 2; ++i)
+ {
+ fixup_key(&key2.keys[i], &session->opt->key_type);
+ }
key2.n = 2;
- key2_print(&key2, key_type, "Master Encrypt", "Master Decrypt");
+ return key2;
+}
+
+/*
+ * Using source entropy from local and remote hosts, mix into
+ * master key.
+ */
+static bool
+generate_key_expansion(struct key_ctx_bi *key,
+ const struct tls_session *session)
+{
+ bool ret = false;
+
+ if (key->initialized)
+ {
+ msg(D_TLS_ERRORS, "TLS Error: key already initialized");
+ goto exit;
+ }
+
+
+ bool server = session->opt->server;
+
+ struct key2 key2 = generate_key_expansion_oepnvpn_prf(session);
+
+ key2_print(&key2, &session->opt->key_type,
+ "Master Encrypt", "Master Decrypt");
/* check for weak keys */
for (int i = 0; i < 2; ++i)
{
- fixup_key(&key2.keys[i], key_type);
- if (!check_key(&key2.keys[i], key_type))
+ if (!check_key(&key2.keys[i], &session->opt->key_type))
{
msg(D_TLS_ERRORS, "TLS Error: Bad dynamic key generated");
goto exit;
}
}
-
- /* Initialize OpenSSL key contexts */
- int key_direction = server ? KEY_DIRECTION_INVERSE : KEY_DIRECTION_NORMAL;
- init_key_ctx_bi(key, &key2, key_direction, key_type, "Data Channel");
-
- /* Initialize implicit IVs */
- key_ctx_update_implicit_iv(&key->encrypt, key2.keys[(int)server].hmac,
- MAX_HMAC_KEY_LENGTH);
- key_ctx_update_implicit_iv(&key->decrypt, key2.keys[1-(int)server].hmac,
- MAX_HMAC_KEY_LENGTH);
-
+ init_key_contexts(key, &session->opt->key_type, server, &key2);
ret = true;
exit:
- secure_memzero(&master, sizeof(master));
secure_memzero(&key2, sizeof(key2));
return ret;
}
+
static void
key_ctx_update_implicit_iv(struct key_ctx *ctx, uint8_t *key, size_t key_len)
{
@@ -1879,10 +1912,7 @@ tls_session_generate_data_channel_keys(struct
tls_session *session)
{
bool ret = false;
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
- const struct session_id *client_sid = session->opt->server ?
- &ks->session_id_remote :
&session->session_id;
- const struct session_id *server_sid = !session->opt->server ?
- &ks->session_id_remote :
&session->session_id;
+
if (ks->authenticated == KS_AUTH_FALSE)
{
@@ -1891,9 +1921,8 @@ tls_session_generate_data_channel_keys(struct tls_session
*session)
}
ks->crypto_options.flags = session->opt->crypto_flags;
- if (!generate_key_expansion(&ks->crypto_options.key_ctx_bi,
- &session->opt->key_type, ks->key_src,
client_sid, server_sid,
- session->opt->server))
+
+ if (!generate_key_expansion(&ks->crypto_options.key_ctx_bi, session))
{
msg(D_TLS_ERRORS, "TLS Error: generate_key_expansion failed");
goto cleanup;
--
2.26.2
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