commit ab5a947d8e514f0df35b7625dc085cb901a2b85b
author Adam Langley <agl@google.com> Thu Jan 25 15:38:20 2018 -0800
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> Fri Jan 26 19:48:03 2018 +0000
tree db3e9d307fcf46038ca0a8373561967ad817a68d
parent c61b5771974781fe859050e68094621d217be025

Reslice TLS AEAD setup.

This change reslices how the functions that generate the key block and
initialise the TLS AEADs are cut. This makes future changes easier.

Change-Id: I7e0f7327375301bed96f33c195b80156db83ce6d
Reviewed-on: https://boringssl-review.googlesource.com/24845
Reviewed-by: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

ssl/t1_enc.cc

diff --git a/ssl/t1_enc.cc b/ssl/t1_enc.cc
index 7f4f10b..d1fb710 100644
--- a/ssl/t1_enc.cc
+++ b/ssl/t1_enc.cc
@@ -239,42 +239,26 @@
   return true;
 }
 
-static bool setup_key_block(SSL_HANDSHAKE *hs) {
-  SSL *const ssl = hs->ssl;
-  if (!hs->key_block.empty()) {
-    return true;
-  }
-
-  size_t mac_secret_len, key_len, fixed_iv_len;
-  Array<uint8_t> key_block;
-  if (!get_key_block_lengths(ssl, &mac_secret_len, &key_len, &fixed_iv_len,
-                             hs->new_cipher) ||
-      !key_block.Init(2 * (mac_secret_len + key_len + fixed_iv_len)) ||
-      !SSL_generate_key_block(ssl, key_block.data(), key_block.size())) {
-    return false;
-  }
-
-  hs->key_block = std::move(key_block);
-  return true;
-}
-
-int tls1_change_cipher_state(SSL_HANDSHAKE *hs,
-                             evp_aead_direction_t direction) {
-  SSL *const ssl = hs->ssl;
-  // Ensure the key block is set up.
+static int tls1_configure_aead(SSL *ssl, evp_aead_direction_t direction,
+                               Array<uint8_t> *key_block_cache,
+                               const SSL_CIPHER *cipher,
+                               Span<const uint8_t> iv_override) {
   size_t mac_secret_len, key_len, iv_len;
-  if (!setup_key_block(hs) ||
-      !get_key_block_lengths(ssl, &mac_secret_len, &key_len, &iv_len,
-                             hs->new_cipher)) {
+  if (!get_key_block_lengths(ssl, &mac_secret_len, &key_len, &iv_len, cipher)) {
     return 0;
   }
 
-  if ((mac_secret_len + key_len + iv_len) * 2 != hs->key_block.size()) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return 0;
+  // Ensure that |key_block_cache| is set up.
+  const size_t key_block_size = 2 * (mac_secret_len + key_len + iv_len);
+  if (key_block_cache->empty()) {
+    if (!key_block_cache->Init(key_block_size) ||
+        !SSL_generate_key_block(ssl, key_block_cache->data(), key_block_size)) {
+      return 0;
+    }
   }
+  assert(key_block_cache->size() == key_block_size);
 
-  Span<const uint8_t> key_block = hs->key_block;
+  Span<const uint8_t> key_block = *key_block_cache;
   Span<const uint8_t> mac_secret, key, iv;
   if (direction == (ssl->server ? evp_aead_open : evp_aead_seal)) {
     // Use the client write (server read) keys.
@@ -288,9 +272,15 @@
     iv = key_block.subspan(2 * mac_secret_len + 2 * key_len + iv_len, iv_len);
   }
 
-  UniquePtr<SSLAEADContext> aead_ctx =
-      SSLAEADContext::Create(direction, ssl->version, SSL_is_dtls(ssl),
-                             hs->new_cipher, key, mac_secret, iv);
+  if (!iv_override.empty()) {
+    if (iv_override.size() != iv_len) {
+      return 0;
+    }
+    iv = iv_override;
+  }
+
+  UniquePtr<SSLAEADContext> aead_ctx = SSLAEADContext::Create(
+      direction, ssl->version, SSL_is_dtls(ssl), cipher, key, mac_secret, iv);
   if (!aead_ctx) {
     return 0;
   }
@@ -302,6 +292,12 @@
   return ssl->method->set_write_state(ssl, std::move(aead_ctx));
 }
 
+int tls1_change_cipher_state(SSL_HANDSHAKE *hs,
+                             evp_aead_direction_t direction) {
+  return tls1_configure_aead(hs->ssl, direction, &hs->key_block,
+                             hs->new_cipher, {});
+}
+
 int tls1_generate_master_secret(SSL_HANDSHAKE *hs, uint8_t *out,
                                 Span<const uint8_t> premaster) {
   static const char kMasterSecretLabel[] = "master secret";